diff --git a/usr.bin/sort/sort.c b/usr.bin/sort/sort.c
--- a/usr.bin/sort/sort.c
+++ b/usr.bin/sort/sort.c
@@ -735,7 +735,7 @@
 	    { false, false, false, false, false, false };
 
 	if (s && *s) {
-		char *sptr;
+		const char *sptr;
 
 		sptr = strchr(s, ',');
 		if (sptr) {