diff --git a/src/debugger.c b/src/debugger.c
index a04a078..393e11e 100644
--- a/src/debugger.c
+++ b/src/debugger.c
@@ -287,7 +287,8 @@
     }
     vim_free(cmdline);
 
-    --RedrawingDisabled;
+    if (RedrawingDisabled > 0)
+	--RedrawingDisabled;
     --no_wait_return;
     redraw_all_later(UPD_NOT_VALID);
     need_wait_return = FALSE;