diff --git a/image/test/mochitest/bug733553.sjs b/image/test/mochitest/bug733553.sjs
index 46d4928cc618..5bf4e4aee940 100644
--- a/image/test/mochitest/bug733553.sjs
+++ b/image/test/mochitest/bug733553.sjs
@@ -43,7 +43,9 @@ function getFileAsInputStream(aFilename) {
 
 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);
diff --git a/image/test/mochitest/test_bug733553.html b/image/test/mochitest/test_bug733553.html
index 2d0cf409a5e0..b91ff4544350 100644
--- a/image/test/mochitest/test_bug733553.html
+++ b/image/test/mochitest/test_bug733553.html
@@ -67,10 +67,10 @@ function imageLoad(aEvent) {
   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();
   }
 }