diff --git a/src/structs.h b/src/structs.h
index 3c2bf3f..7a74e8f 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -2509,7 +2509,8 @@
 #ifdef FEAT_DIFF
     diff_T	    *tp_first_diff;
     buf_T	    *(tp_diffbuf[DB_COUNT]);
-    int		    tp_diff_invalid;	/* list of diffs is outdated */
+    int		    tp_diff_invalid;	// list of diffs is outdated
+    int		    tp_diff_update;	// update diffs before redrawing
 #endif
     frame_T	    *(tp_snapshot[SNAP_COUNT]);  /* window layout snapshots */
 #ifdef FEAT_EVAL