1 files changed, 2 insertions, 0 deletions
diff --git a/mbbsd/screen.c b/mbbsd/screen.c
index c0a389f2..9eabb276 100644
--- a/mbbsd/screen.c
+++ b/mbbsd/screen.c
@@ -27,6 +27,8 @@ initscr(void)
 void
 move(int y, int x)
 {
+    assert(y>=0);
+    assert(x>=0);
     cur_col = x;
     cur_ln = y;
 }