diff --git a/ext/webgpu/01_webgpu.js b/ext/webgpu/01_webgpu.js
index cd1a6e5ad7..3531dd7972 100644
--- a/ext/webgpu/01_webgpu.js
+++ b/ext/webgpu/01_webgpu.js
@@ -174,6 +174,7 @@
       super(message);
     }
   }
+  const GPUValidationErrorPrototype = GPUValidationError.prototype;
 
   class GPU {
     [webidl.brand] = webidl.brand;
@@ -715,7 +716,7 @@
       const validationFilteredPromise = PromisePrototypeCatch(
         operation,
         (err) => {
-          if (ObjectPrototypeIsPrototypeOf.prototype(GPUValidationError, err)) {
+          if (ObjectPrototypeIsPrototypeOf(GPUValidationErrorPrototype, err)) {
             return PromiseReject(err);
           }
           return PromiseResolve();