diff --git a/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java b/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java
index 8717c277047047918acdd95891bd5a86c1586247..71d377abe946e9776fdb9e18262e6111991de33b 100644
--- a/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java
+++ b/test/src/main/java/org/jvnet/hudson/test/HudsonTestCase.java
@@ -1628,7 +1628,7 @@ public abstract class HudsonTestCase extends TestCase implements RootAction {
         public WebClient() {
             // default is IE6, but this causes 'n.doScroll('left')' to fail in event-debug.js:1907 as HtmlUnit doesn't implement such a method,
             // so trying something else, until we discover another problem.
-            super(BrowserVersion.FIREFOX_38);
+            super(BrowserVersion.FIREFOX_24);
 
             setPageCreator(HudsonPageCreator.INSTANCE);
             clients.add(this);