diff --git a/types/scratch-vm.d.ts b/types/scratch-vm.d.ts
index c17a4cb..268f699 100644
--- a/types/scratch-vm.d.ts
+++ b/types/scratch-vm.d.ts
@@ -774,7 +774,7 @@ declare namespace VM {
     /**
      * Load a remote extension. Does not work on scratch.mit.edu.
      */
-    loadExtensionURL(extensionID: string): void;
+    loadExtensionURL(extensionID: string): Promise<number>;
   }
 
   /**