diff --git a/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java b/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java
index 28cc4c0730d3..02f43bc8ba3b 100644
--- a/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java
+++ b/platform/projectModel-impl/src/com/intellij/openapi/roots/impl/ProjectFileIndexImpl.java
@@ -163,7 +163,7 @@ public class ProjectFileIndexImpl extends FileIndexBase implements ProjectFileIn
 
   @Override
   public String getPackageNameByDirectory(@NotNull VirtualFile dir) {
-    LOG.assertTrue(dir.isDirectory());
+    LOG.assertTrue(dir.isDirectory(), dir.getPresentableUrl());
     return myDirectoryIndex.getPackageName(dir);
   }