diff --git a/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java b/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java
index 61d7d8b061cc..51120e62d0c1 100644
--- a/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java
+++ b/platform/core-impl/src/com/intellij/psi/stubs/ObjectStubTree.java
@@ -124,7 +124,7 @@ public class ObjectStubTree<T extends Stub> {
       } else {
         int lastZero;
         for(lastZero = list.length - 1; lastZero >=0 && list[lastZero] == 0; --lastZero);
-        if (list[lastZero] == myStubIdx) {
+        if (lastZero >= 0 && list[lastZero] == myStubIdx) {
           // second and subsequent occurrence calls for the same value are no op
           return;
         }