2 files changed, 18 insertions, 12 deletions
diff --git a/ext/webidl/00_webidl.js b/ext/webidl/00_webidl.js
index a532c5ac4..c3b00286f 100644
--- a/ext/webidl/00_webidl.js
+++ b/ext/webidl/00_webidl.js
@@ -1138,36 +1138,42 @@ function mixinPairIterable(name, prototype, dataSymbol, keyKey, valueKey) {
   return ObjectDefineProperties(prototype.prototype, properties);
 }
 
-function configurePrototype(prototype) {
-  const descriptors = ObjectGetOwnPropertyDescriptors(prototype.prototype);
+function configureInterface(interface_) {
+  configureProperties(interface_);
+  configureProperties(interface_.prototype);
+  ObjectDefineProperty(interface_.prototype, SymbolToStringTag, {
+    value: interface_.name,
+    enumerable: false,
+    configurable: true,
+    writable: false,
+  });
+}
+
+function configureProperties(obj) {
+  const descriptors = ObjectGetOwnPropertyDescriptors(obj);
   for (const key in descriptors) {
     if (!ObjectHasOwn(descriptors, key)) {
       continue;
     }
     if (key === "constructor") continue;
+    if (key === "prototype") continue;
     const descriptor = descriptors[key];
     if (
       ReflectHas(descriptor, "value") &&
       typeof descriptor.value === "function"
     ) {
-      ObjectDefineProperty(prototype.prototype, key, {
+      ObjectDefineProperty(obj, key, {
         enumerable: true,
         writable: true,
         configurable: true,
       });
     } else if (ReflectHas(descriptor, "get")) {
-      ObjectDefineProperty(prototype.prototype, key, {
+      ObjectDefineProperty(obj, key, {
         enumerable: true,
         configurable: true,
       });
     }
   }
-  ObjectDefineProperty(prototype.prototype, SymbolToStringTag, {
-    value: prototype.name,
-    enumerable: false,
-    configurable: true,
-    writable: false,
-  });
 }
 
 const setlikeInner = Symbol("[[set]]");
@@ -1275,7 +1281,7 @@ function setlike(obj, objPrototype, readonly) {
 export {
   assertBranded,
   brand,
-  configurePrototype,
+  configureInterface,
   converters,
   createBranded,
   createDictionaryConverter,
diff --git a/ext/webidl/internal.d.ts b/ext/webidl/internal.d.ts
index 38f176ab2..7f1f68282 100644
--- a/ext/webidl/internal.d.ts
+++ b/ext/webidl/internal.d.ts
@@ -543,7 +543,7 @@ declare module "ext:deno_webidl/00_webidl.js" {
   /**
    * Configure prototype properties enumerability / writability / configurability.
    */
-  function configurePrototype(prototype: any);
+  function configureInterface(prototype: any);
 
   /**
    * Get the WebIDL / ES type of a value.