1 files changed, 2 insertions, 2 deletions
diff --git a/flip.c b/flip.c
index 2ec16ba..6ccd872 100644
--- a/flip.c
+++ b/flip.c
@@ -116,11 +116,11 @@ static game_params *dup_params(game_params *params)
 static void decode_params(game_params *ret, char const *string)
 {
     ret->w = ret->h = atoi(string);
-    while (*string && isdigit(*string)) string++;
+    while (*string && isdigit((unsigned char)*string)) string++;
     if (*string == 'x') {
         string++;
         ret->h = atoi(string);
-        while (*string && isdigit(*string)) string++;
+        while (*string && isdigit((unsigned char)*string)) string++;
     }
     if (*string == 'r') {
         string++;