diff --git a/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java b/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java
index 576b80af610b..01fcccbf1368 100644
--- a/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java
+++ b/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java
@@ -468,7 +468,7 @@ public abstract class UsefulTestCase extends TestCase {
   }
 
   public static <T> T assertInstanceOf(Object o, Class<T> aClass) {
-    Assert.assertNotNull(o);
+    Assert.assertNotNull("Expected instance of: " + aClass.getName() + " actual: " + null, o);
     Assert.assertTrue("Expected instance of: " + aClass.getName() + " actual: " + o.getClass().getName(), aClass.isInstance(o));
     return (T)o;
   }