diff --git a/core/src/main/java/hudson/model/Actionable.java b/core/src/main/java/hudson/model/Actionable.java
index 2319ee3c326d3fdd7b7c2759238e0578b4f92ac6..9df278d5b7f66fe4017b0e65cffdc1d3c203723c 100644
--- a/core/src/main/java/hudson/model/Actionable.java
+++ b/core/src/main/java/hudson/model/Actionable.java
@@ -78,7 +78,10 @@ public abstract class Actionable extends AbstractModelObject {
 
     public Object getDynamic(String token, StaplerRequest req, StaplerResponse rsp) {
         for (Action a : getActions()) {
-            if(a.getUrlName().equals(token))
+            String urlName = a.getUrlName();
+            if(urlName==null)
+                throw new AssertionError("Action "+a+" returned null from the getUrlName() method");
+            if(urlName.equals(token))
                 return a;
         }
         return null;