diff --git a/src/apis/emscripten/mod.rs b/src/apis/emscripten/mod.rs
index 498be032e..9a81eea65 100644
--- a/src/apis/emscripten/mod.rs
+++ b/src/apis/emscripten/mod.rs
@@ -265,6 +265,11 @@ pub fn generate_emscripten_env<'a, 'b>() -> ImportObject<&'a str, &'b str> {
         "___syscall63",
         ImportValue::Func(syscalls::___syscall63 as _),
     );
+    import_object.set(
+        "env",
+        "___syscall142",
+        ImportValue::Func(syscalls::___syscall142 as _),
+    );
 
     // Process
     import_object.set("env", "abort", ImportValue::Func(process::em_abort as _));
@@ -458,7 +463,7 @@ pub fn generate_emscripten_env<'a, 'b>() -> ImportObject<&'a str, &'b str> {
     mock_external!(import_object, ___syscall168);
     // mock_external!(import_object, ___syscall146);
     // mock_external!(import_object, ___syscall145);
-    mock_external!(import_object, ___syscall142);
+    // mock_external!(import_object, ___syscall142);
     mock_external!(import_object, ___syscall140);
     // mock_external!(import_object, ___syscall122);
     // mock_external!(import_object, ___syscall102);
diff --git a/src/apis/emscripten/syscalls.rs b/src/apis/emscripten/syscalls.rs
index 795ab3297..07e1ee299 100644
--- a/src/apis/emscripten/syscalls.rs
+++ b/src/apis/emscripten/syscalls.rs
@@ -50,6 +50,7 @@ use libc::{
     utsname,
     write,
     writev,
+    select,
     FIONBIO,
 };
 
@@ -183,7 +184,9 @@ pub extern "C" fn ___syscall54(
         21537 => { // FIONBIO
             let argp: u32 = varargs.get(instance);
             let argp_ptr = instance.memory_offset_addr(0, argp as _);
-            unsafe { ioctl(fd, FIONBIO, argp_ptr) }
+            let ret = unsafe { ioctl(fd, FIONBIO, argp_ptr) };
+            debug!("ret: {}", ret);
+            ret
         },
         _ => unimplemented!(),
     }
@@ -276,7 +279,11 @@ pub extern "C" fn ___syscall102(
             let address = instance.memory_offset_addr(0, address as usize) as *mut sockaddr;
             let address_len_addr =
                 instance.memory_offset_addr(0, address_len as usize) as *mut socklen_t;
-            unsafe { accept(socket, address, address_len_addr) }
+            let fd = unsafe { accept(socket, address, address_len_addr) };
+            debug!("fd: {}", fd);
+            // nix::unistd::write(fd, "Hello, World!".as_bytes()).unwrap();
+            // nix::unistd::fsync(fd).unwrap();
+            fd
         }
         6 => {
             debug!("socket: getsockname");
@@ -676,3 +683,26 @@ pub extern "C" fn ___syscall63(
 
     unsafe { dup2(src, dst) }
 }
+
+// newselect
+pub extern "C" fn ___syscall142(
+    _which: c_int,
+    mut varargs: VarArgs,
+    instance: &mut Instance,
+) -> c_int {
+    debug!("emscripten::___syscall142");
+
+    let nfds: i32 = varargs.get(instance);
+    let readfds: u32 = varargs.get(instance);
+    let writefds: u32 = varargs.get(instance);
+    let exceptfds: u32 = varargs.get(instance);
+    let _timeout: i32 = varargs.get(instance);
+
+    assert!(nfds <= 64, "`nfds` must be less than or equal to 64");
+    assert!(exceptfds == 0, "`exceptfds` is not supporrted");
+
+    let readfds_ptr = instance.memory_offset_addr(0, readfds as _) as _;
+    let writefds_ptr = instance.memory_offset_addr(0, writefds as _) as _;
+    
+    unsafe { select(nfds, readfds_ptr, writefds_ptr, 0 as _, 0 as _) }
+}
\ No newline at end of file
diff --git a/src/webassembly/memory.rs b/src/webassembly/memory.rs
index c06000819..e0a75b70a 100644
--- a/src/webassembly/memory.rs
+++ b/src/webassembly/memory.rs
@@ -60,15 +60,18 @@ impl LinearMemory {
                 unsafe {
                     mprotect(
                         base,
-                        (initial * Self::PAGE_SIZE) as _,
+                        // (initial * Self::PAGE_SIZE) as _,
+                        Self::DEFAULT_HEAP_SIZE,
                         PROT_READ | PROT_WRITE,
                     )
                 },
                 0
             );
         }
-
+    
         debug!("LinearMemory instantiated");
+        debug!("  - usable: {:#x}..{:#x}", base as usize, (base as usize) + LinearMemory::DEFAULT_HEAP_SIZE);
+        debug!("  - guard: {:#x}..{:#x}", (base as usize) + LinearMemory::DEFAULT_HEAP_SIZE, (base as usize) + LinearMemory::DEFAULT_SIZE);
         Self {
             base,
             current: initial,