diff --git a/layout/base/tests/test_flush_on_paint.html b/layout/base/tests/test_flush_on_paint.html
index 2a2d14beae1..de088b4de87 100644
--- a/layout/base/tests/test_flush_on_paint.html
+++ b/layout/base/tests/test_flush_on_paint.html
@@ -13,6 +13,9 @@
 <pre id="test">
 <script type="application/javascript">
 SimpleTest.waitForExplicitFinish();
+SimpleTest.requestFlakyTimeout("This test deals with painting and invalidation. " +
+                               "Those are tricky to detect, so we have to poll here, which means that we have to rely on flaky timeouts. " +
+                               "This special case is safe because we're only polling for events.");
 
 var iterations = 0;
 var plugin = document.getElementById("plugin");