diff --git a/platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectManagerImpl.java b/platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectManagerImpl.java
index 498cd5bfa3d4..2f08d7e1b7e7 100644
--- a/platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectManagerImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/project/impl/ProjectManagerImpl.java
@@ -697,6 +697,7 @@ public class ProjectManagerImpl extends ProjectManagerEx implements PersistentSt
 
   @Override
   public void unblockReloadingProjectOnExternalChanges() {
+    assert myReloadBlockCount.get() >= 0;
     if (myReloadBlockCount.decrementAndGet() == 0 && myChangedFilesAlarm.isEmpty()) {
       ApplicationManager.getApplication().invokeLater(restartApplicationOrReloadProjectTask, ModalityState.NON_MODAL, ApplicationManager.getApplication().getDisposed());
     }