diff --git a/grep.c b/grep.c
index 0124eb1960..fc2d0c837a 100644
--- a/grep.c
+++ b/grep.c
@@ -452,18 +452,20 @@ static void free_pcre2_pattern(struct grep_pat *p)
 	pcre2_general_context_free(p->pcre2_general_context);
 }
 #else /* !USE_LIBPCRE2 */
-static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt)
+static void compile_pcre2_pattern(struct grep_pat *p UNUSED,
+				  const struct grep_opt *opt UNUSED)
 {
 	die("cannot use Perl-compatible regexes when not compiled with USE_LIBPCRE");
 }
 
-static int pcre2match(struct grep_pat *p, const char *line, const char *eol,
-		regmatch_t *match, int eflags)
+static int pcre2match(struct grep_pat *p UNUSED, const char *line UNUSED,
+		      const char *eol UNUSED, regmatch_t *match UNUSED,
+		      int eflags UNUSED)
 {
 	return 1;
 }
 
-static void free_pcre2_pattern(struct grep_pat *p)
+static void free_pcre2_pattern(struct grep_pat *p UNUSED)
 {
 }