diff --git a/platform/core-impl/src/com/intellij/psi/impl/source/PsiFileImpl.java b/platform/core-impl/src/com/intellij/psi/impl/source/PsiFileImpl.java
index bc60a46cdddd..6cdf2b48d062 100644
--- a/platform/core-impl/src/com/intellij/psi/impl/source/PsiFileImpl.java
+++ b/platform/core-impl/src/com/intellij/psi/impl/source/PsiFileImpl.java
@@ -287,7 +287,9 @@ public abstract class PsiFileImpl extends ElementBase implements PsiFileEx, PsiF
 
   void reportStubAstMismatch(String message, StubTree stubTree) {
     rebuildStub();
-    updateTrees(myTrees.clearStub(STUB_PSI_MISMATCH));
+    synchronized (myPsiLock) {
+      updateTrees(myTrees.clearStub(STUB_PSI_MISMATCH));
+    }
 
     throw StubTreeLoader.getInstance().stubTreeAndIndexDoNotMatch(message, stubTree, this);
   }