diff --git a/src/lib.rs b/src/lib.rs
index 0646a416..969269ed 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1072,7 +1072,7 @@ pub mod __rt {
 
     #[no_mangle]
     pub unsafe extern "C" fn __wbindgen_exn_store(idx: u32) {
-        assert_eq!(GLOBAL_EXNDATA[0], 0);
+        debug_assert_eq!(GLOBAL_EXNDATA[0], 0);
         GLOBAL_EXNDATA[0] = 1;
         GLOBAL_EXNDATA[1] = idx;
     }