diff --git a/src/structs.h b/src/structs.h
index 4d1928e..bb02a75 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -428,6 +428,7 @@
 # endif
 # ifdef FEAT_WINDOWS
     int		split;			/* flags for win_split() */
+    int		tab;			/* > 0 when ":tab" was used */
 # endif
 # if defined(FEAT_GUI_DIALOG) || defined(FEAT_CON_DIALOG)
     int		confirm;		/* TRUE to invoke yes/no dialog */