diff --git a/engine/src/flutter/lib/web_ui/skwasm/library_skwasm_multi_threaded.js b/engine/src/flutter/lib/web_ui/skwasm/library_skwasm_multi_threaded.js
index 0070adaf84b..237ccf38bed 100644
--- a/engine/src/flutter/lib/web_ui/skwasm/library_skwasm_multi_threaded.js
+++ b/engine/src/flutter/lib/web_ui/skwasm/library_skwasm_multi_threaded.js
@@ -43,7 +43,7 @@ mergeInto(LibraryManager.library, {
       if (threadId) {
         PThread.pthreads[threadId].postMessage(message, transfers);
       } else {
-        postMessage(message);
+        postMessage(message, transfers);
       }
     };
   },