X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/puzzles/blobdiff_plain/9ec8a3176a8fe57877548f2226a91d702c63b849..ca2e15e21765c97b56bd971198c3b93866fe82f1:/signpost.c

diff --git a/signpost.c b/signpost.c
index b6db3a3..efed3f7 100644
--- a/signpost.c
+++ b/signpost.c
@@ -513,7 +513,7 @@ static void unpick_desc(game_params *params, char *desc,
         }
 
         c = *desc;
-        if (isdigit(c)) {
+        if (isdigit((unsigned char)c)) {
             num = (num*10) + (int)(c-'0');
             if (num > state->n) {
                 msg = "Number too large";