diff --git a/CHANGELOG.md b/CHANGELOG.md
index 35838a19b..da65b1199 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ Blocks of changes will separated by version increments.
 
 ## **[Unreleased]**
 
+- [#476](https://github.com/wasmerio/wasmer/pull/476) Fix bug with wasi::environ_get, fix off by one error in wasi::environ_sizes_get
 - [#470](https://github.com/wasmerio/wasmer/pull/470) Add mapdir support to Emscripten, implement getdents for Unix
 - [#467](https://github.com/wasmerio/wasmer/pull/467) `wasmer_instantiate` returns better error messages in the runtime C API
 - [#463](https://github.com/wasmerio/wasmer/pull/463) Fix bug in WASI path_open allowing one level above preopened dir to be accessed
diff --git a/Cargo.lock b/Cargo.lock
index 9464d9102..d2c145852 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -34,7 +34,7 @@ name = "atty"
 version = "0.2.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "termion 1.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -52,7 +52,7 @@ dependencies = [
  "autocfg 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "backtrace-sys 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-demangle 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -62,7 +62,7 @@ version = "0.1.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -137,8 +137,8 @@ dependencies = [
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.15.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "tempfile 3.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -169,8 +169,8 @@ version = "0.26.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
- "libloading 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libloading 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -211,19 +211,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "cranelift-bforest"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 dependencies = [
- "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
 ]
 
 [[package]]
 name = "cranelift-codegen"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 dependencies = [
- "cranelift-bforest 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-codegen-meta 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-bforest 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-codegen-meta 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -233,22 +233,22 @@ dependencies = [
 [[package]]
 name = "cranelift-codegen-meta"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 dependencies = [
- "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
 ]
 
 [[package]]
 name = "cranelift-entity"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 
 [[package]]
 name = "cranelift-frontend"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 dependencies = [
- "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "target-lexicon 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -256,9 +256,9 @@ dependencies = [
 [[package]]
 name = "cranelift-native"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 dependencies = [
- "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
  "raw-cpuid 6.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "target-lexicon 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -266,12 +266,12 @@ dependencies = [
 [[package]]
 name = "cranelift-wasm"
 version = "0.30.0"
-source = "git+https://github.com/wasmerio/cranelift.git?branch=wasmer#84ec31b0fdfc10db491ef950815ee2961db057cb"
+source = "git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb#84ec31b0fdfc10db491ef950815ee2961db057cb"
 dependencies = [
  "cast 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-frontend 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-frontend 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -290,15 +290,15 @@ dependencies = [
  "csv 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_os 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_xoshiro 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon-core 1.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "tinytemplate 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -353,7 +353,7 @@ dependencies = [
  "csv-core 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "itoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ryu 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -428,7 +428,7 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "errno-dragonfly 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -438,7 +438,7 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "gcc 0.3.55 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -514,7 +514,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "scopeguard 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -551,7 +551,7 @@ dependencies = [
  "either 1.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "enum-methods 0.0.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "inkwell_internal_macros 0.1.0 (git+https://github.com/wasmerio/inkwell?branch=llvm7-0)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "llvm-sys 70.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -597,12 +597,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "libc"
-version = "0.2.55"
+version = "0.2.57"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "libloading"
-version = "0.5.0"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -616,7 +616,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -643,7 +643,7 @@ name = "memchr"
 version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -651,7 +651,7 @@ name = "memmap"
 version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -660,7 +660,7 @@ name = "memmap"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -677,7 +677,7 @@ dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -689,7 +689,7 @@ dependencies = [
  "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -720,7 +720,7 @@ name = "num_cpus"
 version = "1.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -750,7 +750,7 @@ version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -768,7 +768,7 @@ name = "parking_lot_core"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -821,7 +821,7 @@ version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_chacha 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_hc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -876,7 +876,7 @@ name = "rand_jitter"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -888,7 +888,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -947,7 +947,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1065,10 +1065,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "serde"
-version = "1.0.91"
+version = "1.0.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1077,7 +1077,7 @@ version = "0.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1085,12 +1085,12 @@ name = "serde_bytes"
 version = "0.10.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.91"
+version = "1.0.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1105,7 +1105,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "itoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ryu 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1125,16 +1125,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "structopt"
-version = "0.2.16"
+version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "structopt-derive 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "structopt-derive 0.2.17 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "structopt-derive"
-version = "0.2.16"
+version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1203,7 +1203,7 @@ version = "3.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1223,7 +1223,7 @@ name = "termion"
 version = "1.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "numtoa 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1250,7 +1250,7 @@ name = "time"
 version = "0.1.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.54 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1260,7 +1260,7 @@ name = "tinytemplate"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1269,7 +1269,7 @@ name = "toml"
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 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1327,8 +1327,8 @@ name = "wabt"
 version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "wabt-sys 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1362,7 +1362,7 @@ dependencies = [
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "hashbrown 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "structopt 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "structopt 0.2.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "wabt 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-clif-backend 0.4.2",
  "wasmer-dev-utils 0.4.2",
@@ -1381,19 +1381,19 @@ name = "wasmer-clif-backend"
 version = "0.4.2"
 dependencies = [
  "byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-frontend 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-native 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
- "cranelift-wasm 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)",
+ "cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-frontend 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-native 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
+ "cranelift-wasm 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)",
  "hashbrown 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde-bench 0.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_bytes 0.10.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "target-lexicon 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-runtime-core 0.4.2",
  "wasmer-win-exception-handler 0.4.2",
@@ -1405,7 +1405,7 @@ dependencies = [
 name = "wasmer-dev-utils"
 version = "0.4.2"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1416,7 +1416,7 @@ dependencies = [
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "hashbrown 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "wabt 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1431,7 +1431,7 @@ dependencies = [
 name = "wasmer-kernel-loader"
 version = "0.1.0"
 dependencies = [
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-runtime-core 0.4.2",
 ]
 
@@ -1445,7 +1445,7 @@ dependencies = [
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  "inkwell 0.1.0 (git+https://github.com/wasmerio/inkwell?branch=llvm7-0)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1483,7 +1483,7 @@ name = "wasmer-runtime-c-api"
 version = "0.4.2"
 dependencies = [
  "cbindgen 0.8.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-runtime 0.4.2",
  "wasmer-runtime-core 0.4.2",
 ]
@@ -1500,15 +1500,15 @@ dependencies = [
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  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
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  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde-bench 0.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_bytes 0.10.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmparser 0.29.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1523,7 +1523,7 @@ dependencies = [
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  "hashbrown 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-runtime-core 0.4.2",
@@ -1549,7 +1549,7 @@ dependencies = [
  "generational-arena 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "hashbrown 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-clif-backend 0.4.2",
@@ -1565,7 +1565,7 @@ version = "0.4.2"
 dependencies = [
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  "cmake 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "wasmer-runtime-core 0.4.2",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1582,7 +1582,7 @@ version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1656,13 +1656,13 @@ dependencies = [
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 "checksum cmake 0.1.40 (registry+https://github.com/rust-lang/crates.io-index)" = "2ca4386c8954b76a8415b63959337d940d724b336cabd3afe189c2b51a7e1ff0"
 "checksum constant_time_eq 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8ff012e225ce166d4422e0e78419d901719760f62ae2b7969ca6b564d1b54a9e"
-"checksum cranelift-bforest 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
-"checksum cranelift-codegen 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
-"checksum cranelift-codegen-meta 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
-"checksum cranelift-entity 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
-"checksum cranelift-frontend 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
-"checksum cranelift-native 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
-"checksum cranelift-wasm 0.30.0 (git+https://github.com/wasmerio/cranelift.git?branch=wasmer)" = "<none>"
+"checksum cranelift-bforest 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)" = "<none>"
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+"checksum cranelift-frontend 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)" = "<none>"
+"checksum cranelift-native 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)" = "<none>"
+"checksum cranelift-wasm 0.30.0 (git+https://github.com/wasmerio/cranelift.git?rev=84ec31b0fdfc10db491ef950815ee2961db057cb)" = "<none>"
 "checksum criterion 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "0363053954f3e679645fc443321ca128b7b950a6fe288cf5f9335cc22ee58394"
 "checksum criterion-plot 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "76f9212ddf2f4a9eb2d401635190600656a1f88a932ef53d06e7fa4c7e02fb8e"
 "checksum crossbeam-deque 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f739f8c5363aca78cfb059edf753d8f0d36908c348f3d8d1503f03d8b75d9cf3"
@@ -1698,8 +1698,8 @@ dependencies = [
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 "checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
 "checksum lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "bc5729f27f159ddd61f4df6228e827e86643d4d3e7c32183cb30a1c08f604a14"
-"checksum libc 0.2.55 (registry+https://github.com/rust-lang/crates.io-index)" = "42914d39aad277d9e176efbdad68acb1d5443ab65afe0e0e4f0d49352a950880"
-"checksum libloading 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9c3ad660d7cb8c5822cd83d10897b0f1f1526792737a179e73896152f85b88c2"
+"checksum libc 0.2.57 (registry+https://github.com/rust-lang/crates.io-index)" = "a844cabbd5a77e60403a58af576f0a1baa83c3dd2670be63e615bd24fc58b82d"
+"checksum libloading 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a5692f82b51823e27c4118b3e5c0d98aee9be90633ebc71ad12afef380b50219"
 "checksum llvm-sys 70.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "3a2cb392cf218dbb2d2c4f0fe54b8622871f8897a1d62d24a117dcf540bba124"
 "checksum lock_api 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "62ebf1391f6acad60e5c8b43706dde4582df75c06698ab44511d15016bc2442c"
 "checksum log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c84ec4b527950aa83a329754b01dbe3f58361d1c5efacd1f6d68c494d08a17c6"
@@ -1754,16 +1754,16 @@ dependencies = [
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 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
-"checksum serde 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)" = "a72e9b96fa45ce22a4bc23da3858dfccfd60acd28a25bcd328a98fdd6bea43fd"
+"checksum serde 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)" = "32746bf0f26eab52f06af0d0aa1984f641341d06d8d673c693871da2d188c9be"
 "checksum serde-bench 0.0.7 (registry+https://github.com/rust-lang/crates.io-index)" = "d733da87e79faaac25616e33d26299a41143fd4cd42746cbb0e91d8feea243fd"
 "checksum serde_bytes 0.10.5 (registry+https://github.com/rust-lang/crates.io-index)" = "defbb8a83d7f34cc8380751eeb892b825944222888aff18996ea7901f24aec88"
-"checksum serde_derive 1.0.91 (registry+https://github.com/rust-lang/crates.io-index)" = "101b495b109a3e3ca8c4cbe44cf62391527cdfb6ba15821c5ce80bcd5ea23f9f"
+"checksum serde_derive 1.0.92 (registry+https://github.com/rust-lang/crates.io-index)" = "46a3223d0c9ba936b61c0d2e3e559e3217dbfb8d65d06d26e8b3c25de38bae3e"
 "checksum serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)" = "5a23aa71d4a4d43fdbfaac00eff68ba8a06a51759a89ac3304323e800c4dd40d"
 "checksum smallvec 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)" = "c4488ae950c49d403731982257768f48fada354a5203fe81f9bb6f43ca9002be"
 "checksum stable_deref_trait 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "dba1a27d3efae4351c8051072d619e3ade2820635c3958d826bfea39d59b54c8"
 "checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
-"checksum structopt 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)" = "fa19a5a708e22bb5be31c1b6108a2a902f909c4b9ba85cba44c06632386bc0ff"
-"checksum structopt-derive 0.2.16 (registry+https://github.com/rust-lang/crates.io-index)" = "c6d59d0ae8ef8de16e49e3ca7afa16024a3e0dfd974a75ef93fdc5464e34523f"
+"checksum structopt 0.2.17 (registry+https://github.com/rust-lang/crates.io-index)" = "c767a8971f53d7324583085deee2e230903be09e52fb27df9af94c5cb2b43c31"
+"checksum structopt-derive 0.2.17 (registry+https://github.com/rust-lang/crates.io-index)" = "c57a30c87454ced2186f62f940e981746e8cbbe026d52090c8c4352b636f8235"
 "checksum syn 0.11.11 (registry+https://github.com/rust-lang/crates.io-index)" = "d3b891b9015c88c576343b9b3e41c2c11a51c219ef067b264bd9c8aa9b441dad"
 "checksum syn 0.15.34 (registry+https://github.com/rust-lang/crates.io-index)" = "a1393e4a97a19c01e900df2aec855a29f71cf02c402e2f443b8d2747c25c5dbe"
 "checksum synom 0.11.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a393066ed9010ebaed60b9eafa373d4b1baac186dd7e008555b0f702b51945b6"
diff --git a/Makefile b/Makefile
index ba89c7e4f..13822cce0 100644
--- a/Makefile
+++ b/Makefile
@@ -51,6 +51,7 @@ test:
 	cargo test --all --exclude wasmer-runtime-c-api --exclude wasmer-emscripten --exclude wasmer-spectests --exclude wasmer-singlepass-backend --exclude wasmer-wasi -- $(runargs)
 	# cargo test --all --exclude wasmer-emscripten -- --test-threads=1 $(runargs)
 	cargo test --manifest-path lib/spectests/Cargo.toml --features clif
+	@if [ ! -z "${CIRCLE_JOB}" ]; then rm -f /home/circleci/project/target/debug/deps/libcranelift_wasm* && rm -f /Users/distiller/project/target/debug/deps/libcranelift_wasm*; fi;
 	cargo test --manifest-path lib/spectests/Cargo.toml --features llvm
 	cargo test --manifest-path lib/runtime/Cargo.toml --features llvm
 	cargo build -p wasmer-runtime-c-api
diff --git a/lib/clif-backend/Cargo.toml b/lib/clif-backend/Cargo.toml
index 031387c08..bdcfc1a6a 100644
--- a/lib/clif-backend/Cargo.toml
+++ b/lib/clif-backend/Cargo.toml
@@ -9,11 +9,11 @@ edition = "2018"
 
 [dependencies]
 wasmer-runtime-core = { path = "../runtime-core", version = "0.4.2" }
-cranelift-native = { git = "https://github.com/wasmerio/cranelift.git", branch = "wasmer" }
-cranelift-codegen = { git = "https://github.com/wasmerio/cranelift.git", branch = "wasmer" }
-cranelift-entity = { git = "https://github.com/wasmerio/cranelift.git", branch = "wasmer" }
-cranelift-frontend = { git = "https://github.com/wasmerio/cranelift.git", branch = "wasmer" }
-cranelift-wasm = { git = "https://github.com/wasmerio/cranelift.git", branch = "wasmer" }
+cranelift-native = { git = "https://github.com/wasmerio/cranelift.git", rev = "84ec31b0fdfc10db491ef950815ee2961db057cb" }
+cranelift-codegen = { git = "https://github.com/wasmerio/cranelift.git", rev = "84ec31b0fdfc10db491ef950815ee2961db057cb" }
+cranelift-entity = { git = "https://github.com/wasmerio/cranelift.git", rev = "84ec31b0fdfc10db491ef950815ee2961db057cb" }
+cranelift-frontend = { git = "https://github.com/wasmerio/cranelift.git", rev = "84ec31b0fdfc10db491ef950815ee2961db057cb" }
+cranelift-wasm = { git = "https://github.com/wasmerio/cranelift.git", rev = "84ec31b0fdfc10db491ef950815ee2961db057cb" }
 hashbrown = "0.1"
 target-lexicon = "0.4.0"
 wasmparser = "0.29.2"
diff --git a/lib/runtime/src/cache.rs b/lib/runtime/src/cache.rs
index 967d9a8d8..b6d1d779b 100644
--- a/lib/runtime/src/cache.rs
+++ b/lib/runtime/src/cache.rs
@@ -113,3 +113,54 @@ impl Cache for FileSystemCache {
         Ok(())
     }
 }
+
+#[cfg(all(test, not(feature = "singlepass")))]
+mod tests {
+
+    use super::*;
+    use std::env;
+
+    #[test]
+    fn test_file_system_cache_run() {
+        use crate::{compile, imports, Func};
+        use wabt::wat2wasm;
+
+        static WAT: &'static str = r#"
+            (module
+              (type $t0 (func (param i32) (result i32)))
+              (func $add_one (export "add_one") (type $t0) (param $p0 i32) (result i32)
+                get_local $p0
+                i32.const 1
+                i32.add))
+        "#;
+
+        let wasm = wat2wasm(WAT).unwrap();
+
+        let module = compile(&wasm).unwrap();
+
+        let cache_dir = env::temp_dir();
+        println!("test temp_dir {:?}", cache_dir);
+
+        let mut fs_cache = unsafe {
+            FileSystemCache::new(cache_dir)
+                .map_err(|e| format!("Cache error: {:?}", e))
+                .unwrap()
+        };
+        // store module
+        let key = WasmHash::generate(&wasm);
+        fs_cache.store(key, module.clone()).unwrap();
+
+        // load module
+        let cached_module = fs_cache.load(key).unwrap();
+
+        let import_object = imports! {};
+        let instance = cached_module.instantiate(&import_object).unwrap();
+        let add_one: Func<i32, i32> = instance.func("add_one").unwrap();
+
+        let value = add_one.call(42).unwrap();
+
+        // verify it works
+        assert_eq!(value, 43);
+    }
+
+}
diff --git a/lib/wasi/build/wasitests.rs b/lib/wasi/build/wasitests.rs
index cd3865f5e..c305ee44e 100644
--- a/lib/wasi/build/wasitests.rs
+++ b/lib/wasi/build/wasitests.rs
@@ -58,6 +58,8 @@ pub fn compile(file: &str, ignores: &HashSet<String>) -> Option<String> {
     let result = Command::new(&normalized_name)
         .output()
         .expect("Failed to execute native program");
+
+    std::fs::remove_file(&normalized_name).expect("could not delete executable");
     let wasm_out_name = format!("{}.wasm", &normalized_name);
 
     Command::new("rustc")
@@ -76,25 +78,31 @@ pub fn compile(file: &str, ignores: &HashSet<String>) -> Option<String> {
     };
 
     let src_code = fs::read_to_string(file).expect("read src file");
-    let args = extract_args_from_source_file(&src_code);
+    let args = extract_args_from_source_file(&src_code).unwrap_or_default();
 
-    let mapdir_args = if let Some(a) = args {
-        if !a.mapdir.is_empty() {
-            let mut out_str = String::new();
-            out_str.push_str("vec![");
-            for (alias, real_dir) in a.mapdir {
-                out_str.push_str(&format!(
-                    "(\"{}\".to_string(), \"{}\".to_string()),",
-                    alias, real_dir
-                ));
-            }
-            out_str.push_str("]");
-            out_str
-        } else {
-            "vec![]".to_string()
+    let mapdir_args = {
+        let mut out_str = String::new();
+        out_str.push_str("vec![");
+        for (alias, real_dir) in args.mapdir {
+            out_str.push_str(&format!(
+                "(\"{}\".to_string(), \"{}\".to_string()),",
+                alias, real_dir
+            ));
         }
-    } else {
-        "vec![]".to_string()
+        out_str.push_str("]");
+        out_str
+    };
+
+    let envvar_args = {
+        let mut out_str = String::new();
+        out_str.push_str("vec![");
+
+        for entry in args.envvars {
+            out_str.push_str(&format!("\"{}={}\".to_string(),", entry.0, entry.1));
+        }
+
+        out_str.push_str("]");
+        out_str
     };
 
     let contents = format!(
@@ -104,6 +112,7 @@ fn test_{rs_module_name}() {{
         \"../../{module_path}\",
         \"{rs_module_name}\",
         {mapdir_args},
+        {envvar_args},
         \"../../{test_output_path}\"
     );
 }}
@@ -113,6 +122,7 @@ fn test_{rs_module_name}() {{
         rs_module_name = rs_module_name,
         test_output_path = format!("{}.out", normalized_name),
         mapdir_args = mapdir_args,
+        envvar_args = envvar_args
     );
     let rust_test_filepath = format!(
         concat!(env!("CARGO_MANIFEST_DIR"), "/tests/{}.rs"),
@@ -167,14 +177,16 @@ fn read_ignore_list() -> HashSet<String> {
         .collect()
 }
 
+#[derive(Debug, Default)]
 struct Args {
     pub mapdir: Vec<(String, String)>,
+    pub envvars: Vec<(String, String)>,
 }
 
 /// Pulls args to the program out of a comment at the top of the file starting with "// Args:"
 fn extract_args_from_source_file(source_code: &str) -> Option<Args> {
     if source_code.starts_with("// Args:") {
-        let mut args = Args { mapdir: vec![] };
+        let mut args = Args::default();
         for arg_line in source_code
             .lines()
             .skip(1)
@@ -196,6 +208,13 @@ fn extract_args_from_source_file(source_code: &str) -> Option<Args> {
                         );
                     }
                 }
+                "env" => {
+                    if let [name, val] = &tokenized[2].split('=').collect::<Vec<&str>>()[..] {
+                        args.envvars.push((name.to_string(), val.to_string()));
+                    } else {
+                        eprintln!("Parse error in env {} not parsed correctly", &tokenized[2]);
+                    }
+                }
                 e => {
                     eprintln!("WARN: comment arg: {} is not supported", e);
                 }
diff --git a/lib/wasi/src/syscalls/mod.rs b/lib/wasi/src/syscalls/mod.rs
index 51faaacba..3f2826bb9 100644
--- a/lib/wasi/src/syscalls/mod.rs
+++ b/lib/wasi/src/syscalls/mod.rs
@@ -195,7 +195,13 @@ pub fn clock_time_get(
     let memory = ctx.memory(0);
 
     let out_addr = wasi_try!(time.deref(memory));
-    platform_clock_time_get(clock_id, precision, out_addr)
+    let result = platform_clock_time_get(clock_id, precision, out_addr);
+    debug!(
+        "time: {} => {}",
+        wasi_try!(time.deref(memory)).get(),
+        result
+    );
+    result
 }
 
 /// ### `environ_get()`
@@ -215,7 +221,7 @@ pub fn environ_get(
     let state = get_wasi_state(ctx);
     let memory = ctx.memory(0);
 
-    write_buffer_array(memory, &*state.args, environ, environ_buf)
+    write_buffer_array(memory, &*state.envs, environ, environ_buf)
 }
 
 /// ### `environ_sizes_get()`
@@ -238,8 +244,15 @@ pub fn environ_sizes_get(
 
     let state = get_wasi_state(ctx);
 
-    environ_count.set(state.envs.len() as u32);
-    environ_buf_size.set(state.envs.iter().map(|v| v.len() as u32).sum());
+    let env_var_count = state.envs.len() as u32;
+    let env_buf_size = state.envs.iter().map(|v| v.len() as u32 + 1).sum();
+    environ_count.set(env_var_count);
+    environ_buf_size.set(env_buf_size);
+
+    debug!(
+        "env_var_count: {}, env_buf_size: {}",
+        env_var_count, env_buf_size
+    );
 
     __WASI_ESUCCESS
 }
@@ -1665,7 +1678,7 @@ pub fn proc_raise(ctx: &mut Ctx, sig: __wasi_signal_t) -> __wasi_errno_t {
 /// - `size_t buf_len`
 ///     The number of bytes that will be written
 pub fn random_get(ctx: &mut Ctx, buf: WasmPtr<u8, Array>, buf_len: u32) -> __wasi_errno_t {
-    debug!("wasi::random_get");
+    debug!("wasi::random_get buf_len: {}", buf_len);
     let mut rng = thread_rng();
     let memory = ctx.memory(0);
 
diff --git a/lib/wasi/tests/wasitests/_common.rs b/lib/wasi/tests/wasitests/_common.rs
index 9d01f366f..296e88b48 100644
--- a/lib/wasi/tests/wasitests/_common.rs
+++ b/lib/wasi/tests/wasitests/_common.rs
@@ -1,5 +1,5 @@
 macro_rules! assert_wasi_output {
-    ($file:expr, $name:expr, $mapdir_args:expr, $expected:expr) => {{
+    ($file:expr, $name:expr, $mapdir_args:expr, $envvar_args:expr, $expected:expr) => {{
         use wasmer_dev_utils::stdio::StdioCapturer;
         use wasmer_runtime_core::{backend::Compiler, Func};
         use wasmer_wasi::generate_import_object;
diff --git a/lib/wasi/tests/wasitests/create_dir.rs b/lib/wasi/tests/wasitests/create_dir.rs
index 1980907f2..87a73dc2b 100644
--- a/lib/wasi/tests/wasitests/create_dir.rs
+++ b/lib/wasi/tests/wasitests/create_dir.rs
@@ -5,6 +5,7 @@ fn test_create_dir() {
         "../../wasitests/create_dir.wasm",
         "create_dir",
         vec![],
+        vec![],
         "../../wasitests/create_dir.out"
     );
 }
diff --git a/lib/wasi/tests/wasitests/envvar.rs b/lib/wasi/tests/wasitests/envvar.rs
new file mode 100644
index 000000000..e54e58f40
--- /dev/null
+++ b/lib/wasi/tests/wasitests/envvar.rs
@@ -0,0 +1,10 @@
+#[test]
+fn test_envvar() {
+    assert_wasi_output!(
+        "../../wasitests/envvar.wasm",
+        "envvar",
+        vec![],
+        vec![],
+        "../../wasitests/envvar.out"
+    );
+}
diff --git a/lib/wasi/tests/wasitests/file_metadata.rs b/lib/wasi/tests/wasitests/file_metadata.rs
index a22dc5127..f0b0b33aa 100644
--- a/lib/wasi/tests/wasitests/file_metadata.rs
+++ b/lib/wasi/tests/wasitests/file_metadata.rs
@@ -4,6 +4,7 @@ fn test_file_metadata() {
         "../../wasitests/file_metadata.wasm",
         "file_metadata",
         vec![],
+        vec![],
         "../../wasitests/file_metadata.out"
     );
 }
diff --git a/lib/wasi/tests/wasitests/fs_sandbox_test.rs b/lib/wasi/tests/wasitests/fs_sandbox_test.rs
index f9741f01f..6a9c82efa 100644
--- a/lib/wasi/tests/wasitests/fs_sandbox_test.rs
+++ b/lib/wasi/tests/wasitests/fs_sandbox_test.rs
@@ -4,6 +4,7 @@ fn test_fs_sandbox_test() {
         "../../wasitests/fs_sandbox_test.wasm",
         "fs_sandbox_test",
         vec![],
+        vec![],
         "../../wasitests/fs_sandbox_test.out"
     );
 }
diff --git a/lib/wasi/tests/wasitests/hello.rs b/lib/wasi/tests/wasitests/hello.rs
index ffce165e6..ec0c0a351 100644
--- a/lib/wasi/tests/wasitests/hello.rs
+++ b/lib/wasi/tests/wasitests/hello.rs
@@ -4,6 +4,7 @@ fn test_hello() {
         "../../wasitests/hello.wasm",
         "hello",
         vec![],
+        vec![],
         "../../wasitests/hello.out"
     );
 }
diff --git a/lib/wasi/tests/wasitests/mapdir.rs b/lib/wasi/tests/wasitests/mapdir.rs
index 005a0b083..beddf10c8 100644
--- a/lib/wasi/tests/wasitests/mapdir.rs
+++ b/lib/wasi/tests/wasitests/mapdir.rs
@@ -4,6 +4,7 @@ fn test_mapdir() {
         "../../wasitests/mapdir.wasm",
         "mapdir",
         vec![],
+        vec![],
         "../../wasitests/mapdir.out"
     );
 }
diff --git a/lib/wasi/tests/wasitests/mod.rs b/lib/wasi/tests/wasitests/mod.rs
index 0da7447af..362573068 100644
--- a/lib/wasi/tests/wasitests/mod.rs
+++ b/lib/wasi/tests/wasitests/mod.rs
@@ -6,6 +6,7 @@
 #[macro_use]
 mod _common;
 mod create_dir;
+mod envvar;
 mod file_metadata;
 mod fs_sandbox_test;
 mod hello;
diff --git a/lib/wasi/tests/wasitests/quine.rs b/lib/wasi/tests/wasitests/quine.rs
index 156ded8a4..193b2c19e 100644
--- a/lib/wasi/tests/wasitests/quine.rs
+++ b/lib/wasi/tests/wasitests/quine.rs
@@ -4,6 +4,7 @@ fn test_quine() {
         "../../wasitests/quine.wasm",
         "quine",
         vec![],
+        vec![],
         "../../wasitests/quine.out"
     );
 }
diff --git a/lib/wasi/wasitests/create_dir b/lib/wasi/wasitests/create_dir
deleted file mode 100755
index df15914c9..000000000
Binary files a/lib/wasi/wasitests/create_dir and /dev/null differ
diff --git a/lib/wasi/wasitests/create_dir.wasm b/lib/wasi/wasitests/create_dir.wasm
index f7f86a587..a8ec3cb5a 100755
Binary files a/lib/wasi/wasitests/create_dir.wasm and b/lib/wasi/wasitests/create_dir.wasm differ
diff --git a/lib/wasi/wasitests/envvar.out b/lib/wasi/wasitests/envvar.out
new file mode 100644
index 000000000..67848f4f4
--- /dev/null
+++ b/lib/wasi/wasitests/envvar.out
@@ -0,0 +1,6 @@
+Env vars:
+CAT=2
+DOG=1
+DOG Ok("1")
+DOG_TYPE Err(NotPresent)
+SET VAR Ok("HELLO")
diff --git a/lib/wasi/wasitests/envvar.rs b/lib/wasi/wasitests/envvar.rs
new file mode 100644
index 000000000..a5d8982c6
--- /dev/null
+++ b/lib/wasi/wasitests/envvar.rs
@@ -0,0 +1,38 @@
+// Args:
+// env: DOG=1
+// env: CAT=2
+
+use std::env;
+
+fn get_env_var(var_name: &str) -> Result<String, env::VarError> {
+    #[cfg(not(target = "wasi"))]
+    match var_name {
+        "DOG" => Ok("1".to_string()),
+        "CAT" => Ok("2".to_string()),
+        _ => Err(env::VarError::NotPresent),
+    }
+    #[cfg(target = "wasi")]
+    env::var(var_name)
+}
+
+fn main() {
+    #[cfg(not(target = "wasi"))]
+    let mut env_vars = vec!["DOG=1".to_string(), "CAT=2".to_string()];
+    #[cfg(target = "wasi")]
+    let mut env_vars = env::vars()
+        .map(|(key, value)| format!("{}={}", key, value))
+        .collect::<Vec<String>>();
+
+    env_vars.sort();
+
+    println!("Env vars:");
+    for e in env_vars {
+        println!("{}", e);
+    }
+
+    env::set_var("WASI_ENVVAR_TEST", "HELLO");
+
+    println!("DOG {:?}", get_env_var("DOG"));
+    println!("DOG_TYPE {:?}", get_env_var("DOG_TYPE"));
+    println!("SET VAR {:?}", env::var("WASI_ENVVAR_TEST"));
+}
diff --git a/lib/wasi/wasitests/envvar.wasm b/lib/wasi/wasitests/envvar.wasm
new file mode 100755
index 000000000..14bf02996
Binary files /dev/null and b/lib/wasi/wasitests/envvar.wasm differ
diff --git a/lib/wasi/wasitests/file_metadata b/lib/wasi/wasitests/file_metadata
deleted file mode 100755
index 804d38dd4..000000000
Binary files a/lib/wasi/wasitests/file_metadata and /dev/null differ
diff --git a/lib/wasi/wasitests/file_metadata.wasm b/lib/wasi/wasitests/file_metadata.wasm
index 3b8b4aae1..bc6fe76ff 100755
Binary files a/lib/wasi/wasitests/file_metadata.wasm and b/lib/wasi/wasitests/file_metadata.wasm differ
diff --git a/lib/wasi/wasitests/fs_sandbox_test b/lib/wasi/wasitests/fs_sandbox_test
deleted file mode 100755
index eeddb7b0c..000000000
Binary files a/lib/wasi/wasitests/fs_sandbox_test and /dev/null differ
diff --git a/lib/wasi/wasitests/fs_sandbox_test.wasm b/lib/wasi/wasitests/fs_sandbox_test.wasm
index 31c02714a..e3b55f0c1 100755
Binary files a/lib/wasi/wasitests/fs_sandbox_test.wasm and b/lib/wasi/wasitests/fs_sandbox_test.wasm differ
diff --git a/lib/wasi/wasitests/hello b/lib/wasi/wasitests/hello
deleted file mode 100755
index 702ef3a47..000000000
Binary files a/lib/wasi/wasitests/hello and /dev/null differ
diff --git a/lib/wasi/wasitests/hello.wasm b/lib/wasi/wasitests/hello.wasm
index fa48455cd..58114e759 100755
Binary files a/lib/wasi/wasitests/hello.wasm and b/lib/wasi/wasitests/hello.wasm differ
diff --git a/lib/wasi/wasitests/mapdir b/lib/wasi/wasitests/mapdir
deleted file mode 100755
index 5be49b560..000000000
Binary files a/lib/wasi/wasitests/mapdir and /dev/null differ
diff --git a/lib/wasi/wasitests/mapdir.wasm b/lib/wasi/wasitests/mapdir.wasm
index c5ebd6d9a..a4f32480d 100755
Binary files a/lib/wasi/wasitests/mapdir.wasm and b/lib/wasi/wasitests/mapdir.wasm differ
diff --git a/lib/wasi/wasitests/quine b/lib/wasi/wasitests/quine
deleted file mode 100755
index 6593dbb69..000000000
Binary files a/lib/wasi/wasitests/quine and /dev/null differ
diff --git a/lib/wasi/wasitests/quine.wasm b/lib/wasi/wasitests/quine.wasm
index d11d03add..45d739f04 100755
Binary files a/lib/wasi/wasitests/quine.wasm and b/lib/wasi/wasitests/quine.wasm differ
diff --git a/src/bin/wasmer.rs b/src/bin/wasmer.rs
index 19293e41d..387582aa1 100644
--- a/src/bin/wasmer.rs
+++ b/src/bin/wasmer.rs
@@ -19,7 +19,6 @@ use wasmer_clif_backend::CraneliftCompiler;
 use wasmer_llvm_backend::{
     code::LLVMModuleCodeGenerator,
 };
-use wasmer_middleware_common::metering::Metering;
 use wasmer_runtime::{
     cache::{Cache as BaseCache, FileSystemCache, WasmHash, WASMER_VERSION_HASH},
     error::RuntimeError,
@@ -106,6 +105,10 @@ struct Run {
     #[structopt(long = "mapdir", multiple = true)]
     mapped_dirs: Vec<String>,
 
+    /// Pass custom environment variables
+    #[structopt(long = "env", multiple = true)]
+    env_vars: Vec<String>,
+
     /// Custom code loader
     #[structopt(
         long = "loader",
@@ -231,6 +234,47 @@ fn get_cache_dir() -> PathBuf {
     }
 }
 
+fn get_mapped_dirs(input: &[String]) -> Result<Vec<(String, PathBuf)>, String> {
+    let mut md = vec![];
+    for entry in input.iter() {
+        if let [alias, real_dir] = entry.split(':').collect::<Vec<&str>>()[..] {
+            let pb = PathBuf::from(&real_dir);
+            if let Ok(pb_metadata) = pb.metadata() {
+                if !pb_metadata.is_dir() {
+                    return Err(format!(
+                        "\"{}\" exists, but it is not a directory",
+                        &real_dir
+                    ));
+                }
+            } else {
+                return Err(format!("Directory \"{}\" does not exist", &real_dir));
+            }
+            md.push((alias.to_string(), pb));
+            continue;
+        }
+        return Err(format!(
+            "Directory mappings must consist of two paths separate by a colon. Found {}",
+            &entry
+        ));
+    }
+    Ok(md)
+}
+
+fn get_env_var_args(input: &[String]) -> Result<Vec<(&str, &str)>, String> {
+    let mut ev = vec![];
+    for entry in input.iter() {
+        if let [env_var, value] = entry.split('=').collect::<Vec<&str>>()[..] {
+            ev.push((env_var, value));
+        } else {
+            return Err(format!(
+                "Env vars must be of the form <var_name>=<value>. Found {}",
+                &entry
+            ));
+        }
+    }
+    Ok(ev)
+}
+
 /// Execute a wasm/wat file
 fn execute_wasm(options: &Run) -> Result<(), String> {
     // force disable caching on windows
@@ -239,31 +283,8 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
     #[cfg(not(target_os = "windows"))]
     let disable_cache = options.disable_cache;
 
-    let mapped_dirs = {
-        let mut md = vec![];
-        for entry in options.mapped_dirs.iter() {
-            if let &[alias, real_dir] = &entry.split(':').collect::<Vec<&str>>()[..] {
-                let pb = PathBuf::from(&real_dir);
-                if let Ok(pb_metadata) = pb.metadata() {
-                    if !pb_metadata.is_dir() {
-                        return Err(format!(
-                            "\"{}\" exists, but it is not a directory",
-                            &real_dir
-                        ));
-                    }
-                } else {
-                    return Err(format!("Directory \"{}\" does not exist", &real_dir));
-                }
-                md.push((alias.to_string(), pb));
-                continue;
-            }
-            return Err(format!(
-                "Directory mappings must consist of two paths separate by a colon. Found {}",
-                &entry
-            ));
-        }
-        md
-    };
+    let mapped_dirs = get_mapped_dirs(&options.mapped_dirs[..])?;
+    let env_vars = get_env_var_args(&options.env_vars[..])?;
     let wasm_path = &options.path;
 
     let mut wasm_binary: Vec<u8> = read_file_contents(wasm_path).map_err(|err| {
@@ -290,9 +311,10 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
             let num_str = if let Some(ns) = split.next() {
                 ns
             } else {
-                return Err(format!(
+                return Err(
                     "Can't parse symbol map (expected each entry to be of the form: `0:func_name`)"
-                ));
+                        .to_string(),
+                );
             };
             let num: u32 = num_str.parse::<u32>().map_err(|err| {
                 format!(
@@ -303,9 +325,10 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
             let name_str: String = if let Some(name_str) = split.next() {
                 name_str
             } else {
-                return Err(format!(
+                return Err(
                     "Can't parse symbol map (expected each entry to be of the form: `0:func_name`)"
-                ));
+                        .to_string(),
+                );
             }
             .to_owned();
 
@@ -401,7 +424,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
         // cache.load will return the Module if it's able to deserialize it properly, and an error if:
         // * The file is not found
         // * The file exists, but it's corrupted or can't be converted to a module
-        let module = match cache.load(hash) {
+        match cache.load(hash) {
             Ok(module) => {
                 // We are able to load the module from cache
                 module
@@ -421,8 +444,7 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
 
                 module
             }
-        };
-        module
+        }
     };
 
     if let Some(loader) = options.loader {
@@ -497,7 +519,8 @@ fn execute_wasm(options: &Run) -> Result<(), String> {
                 .cloned()
                 .map(|arg| arg.into_bytes())
                 .collect(),
-                env::vars()
+                env_vars
+                    .into_iter()
                     .map(|(k, v)| format!("{}={}", k, v).into_bytes())
                     .collect(),
                 options.pre_opened_directories.clone(),