diff --git a/src/closure.rs b/src/closure.rs
index 9b3a2dda6..259363a35 100644
--- a/src/closure.rs
+++ b/src/closure.rs
@@ -228,7 +228,7 @@ macro_rules! doit {
                   R: IntoWasmAbi + 'static,
         {
             fn describe() {
-                <&Self>::describe();
+                <&mut Self>::describe();
             }
 
             unsafe fn into_abi(me: *mut Self, extra: &mut Stack) -> u32 {