diff --git a/win/curses/cursdial.c b/win/curses/cursdial.c
index f93707463..021d89e15 100644
--- a/win/curses/cursdial.c
+++ b/win/curses/cursdial.c
@@ -1555,7 +1555,8 @@ menu_get_selections(WINDOW *win, nhmenu *menu, int how)
             }
             /*FALLTHRU*/
         default:
-            if (isdigit(curletter) && !selectors[curletter]
+            if (curletter > 0 && curletter < 256
+                && isdigit(curletter) && !selectors[curletter]
                 && !groupaccels[curletter]) {
                 count = curses_get_count(curletter);
                 /* after count, we know some non-digit is already pending */