diff --git a/platform/chromium/vapi-polyfill.js b/platform/chromium/vapi-polyfill.js
index f6e280e8a..4fc5687f1 100644
--- a/platform/chromium/vapi-polyfill.js
+++ b/platform/chromium/vapi-polyfill.js
@@ -122,7 +122,7 @@ if ( typeof self.Map !== 'function' ) {
         return this._map[k];
     };
 
-    self.Set.prototype.has = function(k) {
+    self.Map.prototype.has = function(k) {
         return this._map[k] !== undefined;
     };