--- a/image/test/mochitest/bug733553.sjs
+++ b/image/test/mochitest/bug733553.sjs
@@ -38,17 +38,19 @@ function getFileAsInputStream(aFilename)
   var fileStream = Components.classes['@mozilla.org/network/file-input-stream;1']
                    .createInstance(Components.interfaces.nsIFileInputStream);
   fileStream.init(file, 1, 0, false);
   return fileStream;
 }
 
 function handleRequest(request, response)
 {
-  setSharedState("next-part", "-1");
+  if (!getSharedState("next-part")) {
+    setSharedState("next-part", "-1");
+  }
   response.setHeader("Content-Type",
                      "multipart/x-mixed-replace;boundary=BOUNDARYOMG", false);
   response.setHeader("Cache-Control", "no-cache", false);
   response.setStatusLine(request.httpVersion, 200, "OK");
   // We're sending parts off in a delayed fashion, to let the tests occur.
   response.processAsync();
   response.write("--BOUNDARYOMG\r\n");
   sendParts(response);

--- a/image/test/mochitest/test_bug733553.html
+++ b/image/test/mochitest/test_bug733553.html
@@ -62,20 +62,20 @@ function readyForNext() {
   loader.src = BASE_URL + ++testIndex;
 }
 
 function imageLoad(aEvent) {
   var [width, fileName] = testParts[testIndex];
   is(aEvent.target.width, width,
      "Test " + testIndex + " " + fileName + " width correct");
 
+  // Always call readyForNext here, as it's the closest we have to a cleanup
+  readyForNext();
   if ((testParts.length - 1) == testIndex) {
     SimpleTest.finish();
-  } else {
-    readyForNext();
   }
 }
 
 </script>
 </pre>
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