diff --git a/lib/prefix.h b/lib/prefix.h
index 6c51186f52..3a768572c4 100644
--- a/lib/prefix.h
+++ b/lib/prefix.h
@@ -526,14 +526,14 @@ static inline int ipv6_martian(const struct in6_addr *addr)
 extern int macstr2prefix_evpn(const char *str, struct prefix_evpn *p);
 
 /* NOTE: This routine expects the address argument in network byte order. */
-static inline int ipv4_martian(const struct in_addr *addr)
+static inline bool ipv4_martian(const struct in_addr *addr)
 {
 	in_addr_t ip = ntohl(addr->s_addr);
 
 	if (IPV4_NET0(ip) || IPV4_NET127(ip) || !ipv4_unicast_valid(addr)) {
-		return 1;
+		return true;
 	}
-	return 0;
+	return false;
 }
 
 static inline bool is_default_prefix4(const struct prefix_ipv4 *p)