diff --git a/test/src/main/java/org/jvnet/hudson/test/TestExtensionLoader.java b/test/src/main/java/org/jvnet/hudson/test/TestExtensionLoader.java
index b95937dbdefaff0ca72ad3e33709613b1507636b..c4a7150e0e41485b820a1170d48a84cd2d0379e0 100644
--- a/test/src/main/java/org/jvnet/hudson/test/TestExtensionLoader.java
+++ b/test/src/main/java/org/jvnet/hudson/test/TestExtensionLoader.java
@@ -93,6 +93,8 @@ public class TestExtensionLoader extends ExtensionFinder {
     }
 
     private boolean isActive(TestEnvironment env, Class<?> extType) {
+        if (env == null || env.testCase == null)
+            return false;
         for (Class<?> outer = extType; outer!=null; outer=outer.getEnclosingClass())
             if (outer.isInstance(env.testCase))
                 return true;      // enclosed