diff --git a/src/globals.h b/src/globals.h
index 8fad523..8f373f6 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -539,6 +539,10 @@
 
 EXTERN win_T	*curwin;	/* currently active window */
 
+#ifdef FEAT_AUTOCMD
+EXTERN win_T	*aucmd_win;	/* window used in aucmd_prepbuf() */
+#endif
+
 /*
  * The window layout is kept in a tree of frames.  topframe points to the top
  * of the tree.