diff --git a/emcclib.js b/emcclib.js
index 8fb9dd8..6991c51 100644
--- a/emcclib.js
+++ b/emcclib.js
@@ -463,6 +463,7 @@ mergeInto(LibraryManager.library, {
         blitters[id] = document.createElement("canvas");
         blitters[id].width = w;
         blitters[id].height = h;
+        return id;
     },
 
     /*