1 files changed, 1 insertions, 1 deletions
diff --git a/re.c b/re.c
index 379ff144..091a7774 100644
--- a/re.c
+++ b/re.c
@@ -583,7 +583,7 @@ again:
 			count--;
 		if (*sp == '-' && do_lint && ! range_warned && count == 1
 		    && sp[-1] != '[' && sp[1] != ']'
-		    && ! isdigit(sp[-1]) && ! isdigit(sp[1])
+		    && ! isdigit((unsigned char) sp[-1]) && ! isdigit((unsigned char) sp[1])
 		    && ! (sp[-2] == '[' && sp[-1] == '^')) {
 			range_warned = TRUE;
 			warning(_("range of the form `[%c-%c]' is locale dependant"),