2 files changed, 6 insertions, 0 deletions
diff --git a/src/library_browser.js b/src/library_browser.js
index d7aba76f..00ee158c 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -98,6 +98,7 @@ mergeInto(LibraryManager.library, {
           b = bb.getBlob();
         }
         var url = Browser.URLObject.createObjectURL(b);
+        assert(typeof url == 'string', 'createObjectURL must return a url as a string');
         var img = new Image();
         img.onload = function() {
           assert(img.complete, 'Image ' + name + ' could not be decoded');
@@ -143,6 +144,7 @@ mergeInto(LibraryManager.library, {
             return fail();
           }
           var url = Browser.URLObject.createObjectURL(b); // XXX we never revoke this!
+          assert(typeof url == 'string', 'createObjectURL must return a url as a string');
           var audio = new Audio();
           audio.addEventListener('canplaythrough', function() { finish(audio) }, false); // use addEventListener due to chromium bug 124926
           audio.onerror = function(event) {
diff --git a/src/library_sdl.js b/src/library_sdl.js
index 56f6a6ef..4cb4ca6f 100644
--- a/src/library_sdl.js
+++ b/src/library_sdl.js
@@ -1547,6 +1547,10 @@ var LibrarySDL = {
   SDL_RemoveTimer: function(id) {
     window.clearTimeout(id);
     return true;
+  },
+
+  SDL_CreateThread: function() {
+    throw 'SDL threads cannot be supported in the web platform because they assume shared state. See emscripten_create_worker etc. for a message-passing concurrency model that does let you run code in another thread.'
   }
 };