diff --git a/sort.c b/sort.c
index cea25aa..87d5d3b 100644
--- a/sort.c
+++ b/sort.c
@@ -114,7 +114,7 @@ linecmp(const char **a, const char **b)
 static int
 parse_flags(char **s, int *flags, int bflag)
 {
-	while (isalpha((int)**s))
+	while (isalpha((int)**s)) {
 		switch (*((*s)++)) {
 		case 'b':
 			*flags |= bflag;