diff --git a/platform/indexing-impl/src/com/intellij/psi/stubs/StubProcessingHelperBase.java b/platform/indexing-impl/src/com/intellij/psi/stubs/StubProcessingHelperBase.java
index 978a6c80c9e4..10059a6adc14 100644
--- a/platform/indexing-impl/src/com/intellij/psi/stubs/StubProcessingHelperBase.java
+++ b/platform/indexing-impl/src/com/intellij/psi/stubs/StubProcessingHelperBase.java
@@ -116,7 +116,7 @@ public abstract class StubProcessingHelperBase {
   /***
    * Returns a message to log when stub tree and index do not match
    */
-  protected abstract String stubTreeAndIndexDoNotMatch(StubTree stubTree,
+  protected abstract Object stubTreeAndIndexDoNotMatch(StubTree stubTree,
                                           PsiFileWithStubSupport psiFile,
                                           List<StubElement<?>> plained,
                                           VirtualFile virtualFile,
diff --git a/platform/lang-impl/src/com/intellij/psi/stubs/StubProcessingHelper.java b/platform/lang-impl/src/com/intellij/psi/stubs/StubProcessingHelper.java
index d1634e92d37e..92844c7d00b1 100644
--- a/platform/lang-impl/src/com/intellij/psi/stubs/StubProcessingHelper.java
+++ b/platform/lang-impl/src/com/intellij/psi/stubs/StubProcessingHelper.java
@@ -35,7 +35,7 @@ public class StubProcessingHelper extends StubProcessingHelperBase {
 
 
   @Override
-  protected String stubTreeAndIndexDoNotMatch(StubTree stubTree,
+  protected Object stubTreeAndIndexDoNotMatch(StubTree stubTree,
                                             PsiFileWithStubSupport psiFile,
                                             List<StubElement<?>> plained,
                                             VirtualFile virtualFile,
@@ -51,6 +51,6 @@ public class StubProcessingHelper extends StubProcessingHelperBase {
                                     new Attachment("stubTree.txt", ((PsiFileStubImpl)stubTree.getRoot()).printTree()),
                                     new Attachment("stubTreeFromIndex.txt", stubTreeFromIndex == null
                                                                             ? "null"
-                                                                            : ((PsiFileStubImpl)stubTreeFromIndex.getRoot()).printTree())).toString();
+                                                                            : ((PsiFileStubImpl)stubTreeFromIndex.getRoot()).printTree()));
   }
 }