diff --git a/tests/content/test_img_width_height.html b/tests/content/test_img_width_height.html
index b748db924f5..4c1c8e25076 100644
--- a/tests/content/test_img_width_height.html
+++ b/tests/content/test_img_width_height.html
@@ -7,6 +7,7 @@
   <img src="test.png"/>
 <script>
 // Testing get/set of image width/height properties
+waitForExplicitFinish();
 
 var img = window.document.getElementsByTagName("img")[0];