patch 8.0.1367
diff --git a/src/beval.c b/src/beval.c
index f8bb6ba..981e5ea 100644
--- a/src/beval.c
+++ b/src/beval.c
@@ -50,7 +50,7 @@
     }
 #endif
     wp = mouse_find_win(&row, &col);
-    if (wp != NULL && row < wp->w_height && col < wp->w_width)
+    if (wp != NULL && row >= 0 && row < wp->w_height && col < wp->w_width)
     {
 	/* Found a window and the cursor is in the text.  Now find the line
 	 * number. */