diff --git a/utils.h b/utils.h
index 68c486c..1147ebb 100644
--- a/utils.h
+++ b/utils.h
@@ -18,9 +18,11 @@
 #ifdef __GNUC__
 # define NORETURN __attribute__((noreturn))
 # define NONNULL __attribute__((returns_nonnull))
+# define UNUSED __attribute__((unused))
 #else
 # define NORETURN
 # define NONNULL
+# define UNUSED
 #endif
 #if defined __GNUC__ && !defined __clang__
 # define MALLOC_FREE __attribute__((malloc(free)))
diff --git a/whois.c b/whois.c
index 0a06b76..c4b9742 100644
--- a/whois.c
+++ b/whois.c
@@ -1145,7 +1145,7 @@ int connect_with_timeout(int fd, const struct sockaddr *addr,
     return 0;
 }
 
-void NORETURN alarm_handler(int signum)
+void NORETURN alarm_handler(UNUSED int signum)
 {
     close(sockfd);
     err_quit(_("Timeout."));