diff --git a/lib/options.c b/lib/options.c
index dd9f7180..5ec32302 100644
--- a/lib/options.c
+++ b/lib/options.c
@@ -263,6 +263,8 @@ int mosquitto_opts_set(struct mosquitto *mosq, enum mosq_opt_t option, void *val
 				mosq->protocol = mosq_p_mqtt31;
 			}else if(ival == MQTT_PROTOCOL_V311){
 				mosq->protocol = mosq_p_mqtt311;
+			}else if(ival == MQTT_PROTOCOL_V5){
+				mosq->protocol = mosq_p_mqtt5;
 			}else{
 				return MOSQ_ERR_INVAL;
 			}
diff --git a/lib/send_connect.c b/lib/send_connect.c
index ef83a143..2295e9b0 100644
--- a/lib/send_connect.c
+++ b/lib/send_connect.c
@@ -60,12 +60,15 @@ int send__connect(struct mosquitto *mosq, uint16_t keepalive, bool clean_session
 	password = mosq->password;
 #endif
 
-	if(mosq->protocol == mosq_p_mqtt31){
-		version = MQTT_PROTOCOL_V31;
-		headerlen = 12;
+	if(mosq->protocol == mosq_p_mqtt5){
+		version = MQTT_PROTOCOL_V5;
+		headerlen = 11; /* FIXME - this has a fixed property length of 0 */
 	}else if(mosq->protocol == mosq_p_mqtt311){
 		version = MQTT_PROTOCOL_V311;
 		headerlen = 10;
+	}else if(mosq->protocol == mosq_p_mqtt31){
+		version = MQTT_PROTOCOL_V31;
+		headerlen = 12;
 	}else{
 		return MOSQ_ERR_INVAL;
 	}
@@ -98,7 +101,7 @@ int send__connect(struct mosquitto *mosq, uint16_t keepalive, bool clean_session
 	/* Variable header */
 	if(version == MQTT_PROTOCOL_V31){
 		packet__write_string(packet, PROTOCOL_NAME_v31, strlen(PROTOCOL_NAME_v31));
-	}else if(version == MQTT_PROTOCOL_V311){
+	}else{
 		packet__write_string(packet, PROTOCOL_NAME, strlen(PROTOCOL_NAME));
 	}
 #if defined(WITH_BROKER) && defined(WITH_BRIDGE)
@@ -121,6 +124,11 @@ int send__connect(struct mosquitto *mosq, uint16_t keepalive, bool clean_session
 	packet__write_byte(packet, byte);
 	packet__write_uint16(packet, keepalive);
 
+	if(mosq->protocol == mosq_p_mqtt5){
+		/* Write properties */
+		packet__write_byte(packet, 0); /* FIXME - No properties yet. */
+	}
+
 	/* Payload */
 	packet__write_string(packet, clientid, strlen(clientid));
 	if(will){
diff --git a/src/handle_connect.c b/src/handle_connect.c
index 55310459..d03d1473 100644
--- a/src/handle_connect.c
+++ b/src/handle_connect.c
@@ -183,7 +183,11 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 		}
 		context->protocol = mosq_p_mqtt31;
 	}else if(!strcmp(protocol_name, PROTOCOL_NAME)){
-		if((protocol_version&0x7F) != PROTOCOL_VERSION_v311){
+		if((protocol_version&0x7F) == PROTOCOL_VERSION_v311){
+			context->protocol = mosq_p_mqtt311;
+		}else if((protocol_version&0x7F) == PROTOCOL_VERSION_v5){
+			context->protocol = mosq_p_mqtt5;
+		}else{
 			if(db->config->connection_messages == true){
 				log__printf(NULL, MOSQ_LOG_INFO, "Invalid protocol version %d in CONNECT from %s.",
 						protocol_version, context->address);
@@ -197,7 +201,6 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 			rc = MOSQ_ERR_PROTOCOL;
 			goto handle_connect_error;
 		}
-		context->protocol = mosq_p_mqtt311;
 	}else{
 		if(db->config->connection_messages == true){
 			log__printf(NULL, MOSQ_LOG_INFO, "Invalid protocol \"%s\" in CONNECT from %s.",
@@ -211,7 +214,7 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 		rc = 1;
 		goto handle_connect_error;
 	}
-	if(context->protocol == mosq_p_mqtt311){
+	if(context->protocol == mosq_p_mqtt311 || context->protocol == mosq_p_mqtt5){
 		if((connect_flags & 0x01) != 0x00){
 			rc = MOSQ_ERR_PROTOCOL;
 			goto handle_connect_error;
@@ -236,6 +239,20 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 		goto handle_connect_error;
 	}
 
+	if(protocol_version == PROTOCOL_VERSION_v5){
+		/* FIXME */
+		uint32_t property_len;
+		if(packet__read_varint(&context->in_packet, &property_len)){
+			rc = 1;
+			goto handle_connect_error;
+		}
+		if(property_len != 0){
+			/* FIXME Temporary fudge because of no property support */
+			rc = 1;
+			goto handle_connect_error;
+		}
+	}
+
 	if(packet__read_string(&context->in_packet, &client_id, &slen)){
 		rc = 1;
 		goto handle_connect_error;
@@ -246,7 +263,7 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 			send__connack(context, 0, CONNACK_REFUSED_IDENTIFIER_REJECTED);
 			rc = MOSQ_ERR_PROTOCOL;
 			goto handle_connect_error;
-		}else{ /* mqtt311 */
+		}else{ /* mqtt311/mqtt5 */
 			mosquitto__free(client_id);
 			client_id = NULL;
 
@@ -348,7 +365,7 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 			}
 		}
 	}else{
-		if(context->protocol == mosq_p_mqtt311){
+		if(context->protocol == mosq_p_mqtt311 || context->protocol == mosq_p_mqtt5){
 			if(will_qos != 0 || will_retain != 0){
 				rc = MOSQ_ERR_PROTOCOL;
 				goto handle_connect_error;
@@ -373,7 +390,7 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 					if(context->protocol == mosq_p_mqtt31){
 						/* Password flag given, but no password. Ignore. */
 						password_flag = 0;
-					}else if(context->protocol == mosq_p_mqtt311){
+					}else{
 						rc = MOSQ_ERR_PROTOCOL;
 						goto handle_connect_error;
 					}
@@ -386,13 +403,13 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 			if(context->protocol == mosq_p_mqtt31){
 				/* Username flag given, but no username. Ignore. */
 				username_flag = 0;
-			}else if(context->protocol == mosq_p_mqtt311){
+			}else{
 				rc = MOSQ_ERR_PROTOCOL;
 				goto handle_connect_error;
 			}
 		}
 	}else{
-		if(context->protocol == mosq_p_mqtt311){
+		if(context->protocol == mosq_p_mqtt311 || context->protocol == mosq_p_mqtt5){
 			if(password_flag){
 				/* username_flag == 0 && password_flag == 1 is forbidden */
 				rc = MOSQ_ERR_PROTOCOL;
@@ -568,7 +585,7 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 			}
 		}
 
-		if(context->protocol == mosq_p_mqtt311){
+		if(context->protocol == mosq_p_mqtt311 || context->protocol == mosq_p_mqtt5){
 			if(clean_session == 0){
 				connect_ack |= 0x01;
 			}
@@ -664,7 +681,7 @@ int handle__connect(struct mosquitto_db *db, struct mosquitto *context)
 			if(context->username){
 				log__printf(NULL, MOSQ_LOG_NOTICE, "New client connected from %s as %s (c%d, k%d, u'%s').", context->address, client_id, clean_session, context->keepalive, context->username);
 			}else{
-				log__printf(NULL, MOSQ_LOG_NOTICE, "New client connected from %s as %s (c%d, k%d).", context->address, client_id, clean_session, context->keepalive);
+				log__printf(NULL, MOSQ_LOG_NOTICE, "New client connected from %s as %s (p%d, c%d, k%d).", context->address, client_id, context->protocol, clean_session, context->keepalive);
 			}
 		}
 
@@ -721,7 +738,7 @@ int handle__disconnect(struct mosquitto_db *db, struct mosquitto *context)
 		return MOSQ_ERR_PROTOCOL;
 	}
 	log__printf(NULL, MOSQ_LOG_DEBUG, "Received DISCONNECT from %s", context->id);
-	if(context->protocol == mosq_p_mqtt311){
+	if(context->protocol == mosq_p_mqtt311 || context->protocol == mosq_p_mqtt5){
 		if((context->in_packet.command&0x0F) != 0x00){
 			do_disconnect(db, context);
 			return MOSQ_ERR_PROTOCOL;
diff --git a/src/subs.c b/src/subs.c
index 0716fe19..83eeeafd 100644
--- a/src/subs.c
+++ b/src/subs.c
@@ -266,7 +266,7 @@ static int sub__add_recurse(struct mosquitto_db *db, struct mosquitto *context,
 					if(context->protocol == mosq_p_mqtt31){
 						return -1;
 					}else{
-						/* mqttv311 requires retained messages are resent on
+						/* mqttv311/mqttv5 requires retained messages are resent on
 						 * resubscribe. */
 						return 0;
 					}