diff --git a/layout/style/test/test_visited_pref.html b/layout/style/test/test_visited_pref.html
index 0ad9f41a9d43..22206bb4093f 100644
--- a/layout/style/test/test_visited_pref.html
+++ b/layout/style/test/test_visited_pref.html
@@ -24,6 +24,8 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=147777
 
 /** Test for Bug 147777 **/
 
+// NOTE: this test will fail when ran by itself because the URL is different!
+
 function reinsert_node(e) {
   var sib = e.nextSibling;
   var par = e.parentNode;
@@ -50,8 +52,20 @@ function set_pref(val)
 
 is(get_pref(), true, "pref defaults to true");
 
+// Link coloring is asynchronous (and non-deterministic), so we wait until it
+// changes.
+var thread = Components.classes["@mozilla.org/thread-manager;1"].
+               getService(Components.interfaces.nsIThreadManager).
+               mainThread;
 var link = document.getElementById("mylink");
-var cs = getComputedStyle(link, "");
+var cs;
+var start = Date.now();
+do {
+  while (thread.hasPendingEvents())
+    thread.processNextEvent(false);
+  cs = getComputedStyle(link, "");
+} while(cs.cssFloat != "right");
+var end = Date.now();
 is(cs.cssFloat, "right", ":visited selector applies given default preferences");
 
 set_pref(false);
@@ -60,10 +74,17 @@ set_pref(false);
 // when a new page loads
 reinsert_node(link);
 
-is(cs.cssFloat, "left", ":visited selector does not apply given false preference");
+// Wait a while to make sure we don't update the style on our reinserted node.
+setTimeout(function() {
+  is(cs.cssFloat, "left", ":visited selector does not apply given false preference");
 
-// Set the pref back for the rest of the tests.
-set_pref(true);
+  // Set the pref back for the rest of the tests.
+  set_pref(true);
+
+  SimpleTest.finish();
+}, 10 * Math.max(end - start, 100));
+
+SimpleTest.waitForExplicitFinish();
 
 </script>
 </pre>