diff --git a/platform/platform-impl/src/com/intellij/openapi/command/impl/UndoManagerImpl.java b/platform/platform-impl/src/com/intellij/openapi/command/impl/UndoManagerImpl.java
index 1396c19d7773..bac8125fc1d5 100644
--- a/platform/platform-impl/src/com/intellij/openapi/command/impl/UndoManagerImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/command/impl/UndoManagerImpl.java
@@ -291,6 +291,10 @@ public class UndoManagerImpl extends UndoManager {
   }
 
   public void markCurrentCommandAsGlobal() {
+    if (myCurrentMerger == null) {
+      LOG.error("Must be called inside command");
+      return;
+    }
     myCurrentMerger.markAsGlobal();
   }