1 files changed, 1 insertions, 1 deletions

diff --git a/src/miscbltin.c b/src/miscbltin.c
index be746b2..ec9872d 100644
--- a/src/miscbltin.c
+++ b/src/miscbltin.c
@@ -237,7 +237,7 @@ umaskcmd(int argc, char **argv)
 	} else {
 		int new_mask;
 
-		if (isdigit(*ap)) {
+		if (isdigit((unsigned char) *ap)) {
 			new_mask = 0;
 			do {
 				if (*ap >= '8' || *ap < '0')