diff --git a/include/haproxy/protocol.h b/include/haproxy/protocol.h
index 828093d98..a6c50ceb5 100644
--- a/include/haproxy/protocol.h
+++ b/include/haproxy/protocol.h
@@ -28,6 +28,7 @@
 
 /* [AF][sock_dgram][ctrl_dgram] */
 extern struct protocol *__protocol_by_family[AF_CUST_MAX][PROTO_NUM_TYPES][2];
+extern const struct proto_fam *__proto_fam_by_family[AF_CUST_MAX];
 __decl_thread(extern HA_SPINLOCK_T proto_lock);
 
 /* Registers the protocol <proto> */
@@ -101,6 +102,17 @@ static inline struct protocol *protocol_lookup(int family, enum proto_type proto
 	return NULL;
 }
 
+/* returns the proto_fam that matches ss_family. This supports custom address
+ * families so it is suitable for use with ss_family as found in various config
+ * element addresses.
+ */
+static inline const struct proto_fam *proto_fam_lookup(int ss_family)
+{
+	if (ss_family >= 0 && ss_family < AF_CUST_MAX)
+		return __proto_fam_by_family[ss_family];
+	return NULL;
+}
+
 #endif /* _HAPROXY_PROTOCOL_H */
 
 /*
diff --git a/src/protocol.c b/src/protocol.c
index 69f4595bb..516c020d1 100644
--- a/src/protocol.c
+++ b/src/protocol.c
@@ -28,6 +28,7 @@
 /* List head of all registered protocols */
 static struct list protocols = LIST_HEAD_INIT(protocols);
 struct protocol *__protocol_by_family[AF_CUST_MAX][PROTO_NUM_TYPES][2] __read_mostly = { };
+const struct proto_fam *__proto_fam_by_family[AF_CUST_MAX] = { };
 
 /* This is the global spinlock we may need to register/unregister listeners or
  * protocols. Its main purpose is in fact to serialize the rare stop/deinit()
@@ -48,6 +49,7 @@ void protocol_register(struct protocol *proto)
 	__protocol_by_family[sock_family]
 	                    [proto->proto_type]
 	                    [proto->xprt_type == PROTO_TYPE_DGRAM] = proto;
+	__proto_fam_by_family[sock_family] = proto->fam;
 	HA_SPIN_UNLOCK(PROTO_LOCK, &proto_lock);
 }