diff --git a/lib/vm/src/vmcontext.rs b/lib/vm/src/vmcontext.rs
index dcb5b0cd699..520d100d215 100644
--- a/lib/vm/src/vmcontext.rs
+++ b/lib/vm/src/vmcontext.rs
@@ -23,6 +23,7 @@ use wasmer_types::RawValue;
 /// It may either be a pointer to the [`VMContext`] if it's a Wasm function
 /// or a pointer to arbitrary data controlled by the host if it's a host function.
 #[derive(Copy, Clone, Eq)]
+#[repr(C)]
 pub union VMFunctionContext {
     /// Wasm functions take a pointer to [`VMContext`].
     pub vmctx: *mut VMContext,