diff --git a/src/core/stack_switching/calculate_wasm_func_nargs_fallback.mjs b/src/core/stack_switching/calculate_wasm_func_nargs_fallback.mjs
index 42e98a2791e7..5e20ec3af9f0 100644
--- a/src/core/stack_switching/calculate_wasm_func_nargs_fallback.mjs
+++ b/src/core/stack_switching/calculate_wasm_func_nargs_fallback.mjs
@@ -81,7 +81,7 @@ export function calculateWasmFuncNargsFallback(functionPtr) {
     } catch (e) {
       // Should be a LinkError, if not we have a logic error. Raise fatal error
       // so it's noisy.
-      if (!e instanceof WebAssembly.LinkError) {
+      if ((!e) instanceof WebAssembly.LinkError) {
         throw e;
       }
     }