--- a/dom/media/tests/mochitest/head.js
+++ b/dom/media/tests/mochitest/head.js
@@ -833,25 +833,26 @@ VideoStreamHelper.prototype = {
         // ignore; stream might have shut down, and we don't bother clearing
         // the setInterval.
       }
     }, 100);
   },
 
   waitForFrames: function(canvas, timeout_value) {
     var intervalId = this.startCapturingFrames();
+    timeout_value = timeout_value || 8000;
 
     return addFinallyToPromise(timeout(
       Promise.all([
         this._helper.waitForPixelColor(canvas, this._helper.green, 128,
                                        canvas.id + " should become green"),
         this._helper.waitForPixelColor(canvas, this._helper.red, 128,
                                        canvas.id + " should become red")
       ]),
-      2000,
+      timeout_value,
       "Timed out waiting for frames")).finally(() => clearInterval(intervalId));
   },
 
   verifyNoFrames: function(canvas) {
     return this.waitForFrames(canvas).then(
       () => ok(false, "Color should not change"),
       () => ok(true, "Color should not change")
     );