diff --git a/src/webassembly/instance.rs b/src/webassembly/instance.rs
index fc218ceb5..4b82d3ee5 100644
--- a/src/webassembly/instance.rs
+++ b/src/webassembly/instance.rs
@@ -392,12 +392,20 @@ impl Instance {
         // Instantiate memories
         {
             // Allocate the underlying memory and initialize it to all zeros.
-            memories.reserve_exact(module.info.memories.len());
-            for memory in &module.info.memories {
-                let memory = memory.entity;
-                let v =
-                    LinearMemory::new(memory.pages_count as u32, memory.maximum.map(|m| m as u32));
-                memories.push(v);
+            let total_memories = module.info.memories.len();
+            if total_memories > 0 {
+                memories.reserve_exact(total_memories);
+                for memory in &module.info.memories {
+                    let memory = memory.entity;
+                    let v = LinearMemory::new(
+                        memory.pages_count as u32,
+                        memory.maximum.map(|m| m as u32),
+                    );
+                    memories.push(v);
+                }
+            } else {
+                memories.reserve_exact(1);
+                memories.push(LinearMemory::new(0, None));
             }
             for init in &module.info.data_initializers {
                 debug_assert!(init.base.is_none(), "globalvar base not supported yet");
diff --git a/src/webassembly/memory.rs b/src/webassembly/memory.rs
index 68e44291b..dcc5b816e 100644
--- a/src/webassembly/memory.rs
+++ b/src/webassembly/memory.rs
@@ -40,7 +40,7 @@ impl LinearMemory {
             Some(val) => val as u64,
             None => initial as u64,
         };
-        let len = if len == 0 { 1 } else { len };
+        let len = if len == 0 { PAGE_SIZE as u64 } else { len };
 
         let mmap = MmapMut::map_anon(len as usize).unwrap();
         debug!("LinearMemory instantiated");