1 files changed, 2 insertions, 1 deletions
diff --git a/grep.c b/grep.c
index 4bd1b8b..bb548ca 100644
--- a/grep.c
+++ b/grep.c
@@ -625,7 +625,8 @@ static struct grep_expr *prep_header_patterns(struct grep_opt *opt)
 	for (p = opt->header_list; p; p = p->next) {
 		if (p->token != GREP_PATTERN_HEAD)
 			die("bug: a non-header pattern in grep header list.");
-		if (p->field < 0 || GREP_HEADER_FIELD_MAX <= p->field)
+		if (p->field < GREP_HEADER_FIELD_MIN ||
+		    GREP_HEADER_FIELD_MAX <= p->field)
 			die("bug: unknown header field %d", p->field);
 		compile_regexp(p, opt);
 	}