diff --git a/platform/lang-impl/src/com/intellij/openapi/roots/impl/DirectoryIndexImpl.java b/platform/lang-impl/src/com/intellij/openapi/roots/impl/DirectoryIndexImpl.java
index a2cd94980c68..581e55b2b4ce 100644
--- a/platform/lang-impl/src/com/intellij/openapi/roots/impl/DirectoryIndexImpl.java
+++ b/platform/lang-impl/src/com/intellij/openapi/roots/impl/DirectoryIndexImpl.java
@@ -783,7 +783,7 @@ public class DirectoryIndexImpl extends DirectoryIndex {
             assert VfsUtilCore.isAncestor(contentRoot, file, false) : "File: "+file+"; Content root: "+contentRoot;
         }
       }
-      assert id > 0;
+      assert id > 0 : id;
       myDirToInfoMap.put(id, info);
     }