diff --git a/src/apps/mqtt/mqtt.c b/src/apps/mqtt/mqtt.c
index e36e33a4..5addb2fc 100644
--- a/src/apps/mqtt/mqtt.c
+++ b/src/apps/mqtt/mqtt.c
@@ -2,6 +2,8 @@
  * @file
  * MQTT client
  *
+ * @defgroup mqtt MQTT Client
+ * @ingroup apps
  */
 
 /*
@@ -51,7 +53,7 @@
 #include "lwip/err.h"
 #include "lwip/pbuf.h"
 #include "lwip/tcp.h"
-#include "mqtt.h"
+#include "lwip/apps/mqtt.h"
 
 /**
  * MQTT_DEBUG: Default is off.
@@ -139,7 +141,7 @@ enum mqtt_connect_flag {
 };
 
 
-#if (MQTT_DEBUG == LWIP_DBG_ON) && defined(LWIP_DEBUG)
+#if defined(LWIP_DEBUG)
 static const char * const mqtt_message_type_str[15] =
 {
   "UNDEFINED",
@@ -223,11 +225,11 @@ msg_generate_packet_id(mqtt_client_t *client)
 static void
 mqtt_output_send(struct mqtt_ringbuf_t *rb, struct tcp_pcb *tpcb)
 {
-  LWIP_ASSERT("mqtt_output_send: tpcb != NULL", tpcb != NULL);
   err_t err;
   u8_t wrap = 0;
   u16_t ringbuf_lin_len = mqtt_ringbuf_linear_read_length(rb);
   u16_t send_len = tcp_sndbuf(tpcb);
+  LWIP_ASSERT("mqtt_output_send: tpcb != NULL", tpcb != NULL);
 
   if(send_len == 0 || ringbuf_lin_len == 0) {
     return;
@@ -275,9 +277,9 @@ mqtt_output_send(struct mqtt_ringbuf_t *rb, struct tcp_pcb *tpcb)
 static struct mqtt_request_t *
 mqtt_create_request(struct mqtt_request_t *r_objs, u16_t pkt_id, mqtt_request_cb_t cb, void *arg)
 {
-  LWIP_ASSERT("mqtt_create_request: r_objs != NULL", r_objs != NULL);
   struct mqtt_request_t *r = NULL;
   u8_t n;
+  LWIP_ASSERT("mqtt_create_request: r_objs != NULL", r_objs != NULL);
   for(n = 0; n < MQTT_REQ_MAX_IN_FLIGHT && r == NULL; n++) {
     /* Item point to itself if not in use */
     if(r_objs[n].next == &r_objs[n]) {
@@ -300,12 +302,12 @@ mqtt_create_request(struct mqtt_request_t *r_objs, u16_t pkt_id, mqtt_request_cb
 static void
 mqtt_append_request(struct mqtt_request_t **tail, struct mqtt_request_t *r)
 {
-  LWIP_ASSERT("mqtt_append_request: tail != NULL", tail != NULL);
-
   struct mqtt_request_t *head = NULL;
   s16_t time_before = 0;
   struct mqtt_request_t *iter = *tail;
 
+  LWIP_ASSERT("mqtt_append_request: tail != NULL", tail != NULL);
+
   /* Iterate trough queue to find head, and count total timeout time */
   for(iter = *tail; iter != NULL; iter = iter->next) {
     time_before += iter->timeout_diff;
@@ -343,8 +345,8 @@ mqtt_delete_request(struct mqtt_request_t *r)
 static struct mqtt_request_t *
 mqtt_take_request(struct mqtt_request_t **tail, u16_t pkt_id)
 {
-  LWIP_ASSERT("mqtt_take_request: tail != NULL", tail != NULL);
   struct mqtt_request_t *iter = NULL, *prev = NULL;
+  LWIP_ASSERT("mqtt_take_request: tail != NULL", tail != NULL);
   /* Search all request for pkt_id */
   for(iter = *tail; iter != NULL; iter = iter->next) {
     if(iter->pkt_id == pkt_id) {
@@ -378,8 +380,8 @@ mqtt_take_request(struct mqtt_request_t **tail, u16_t pkt_id)
 static void
 mqtt_request_time_elapsed(struct mqtt_request_t **tail, u8_t t)
 {
-  LWIP_ASSERT("mqtt_request_time_elapsed: tail != NULL", tail != NULL);
   struct mqtt_request_t *r = *tail;
+  LWIP_ASSERT("mqtt_request_time_elapsed: tail != NULL", tail != NULL);
   while(t > 0 && r != NULL) {
     if(t >= r->timeout_diff) {
       t -= r->timeout_diff;
@@ -406,8 +408,8 @@ mqtt_request_time_elapsed(struct mqtt_request_t **tail, u8_t t)
 static void
 mqtt_clear_requests(struct mqtt_request_t **tail)
 {
-  LWIP_ASSERT("mqtt_clear_requests: tail != NULL", tail != NULL);
   struct mqtt_request_t *iter, *next;
+  LWIP_ASSERT("mqtt_clear_requests: tail != NULL", tail != NULL);
   for(iter = *tail; iter != NULL; iter = next) {
     next = iter->next;
     mqtt_delete_request(iter);
@@ -421,8 +423,8 @@ mqtt_clear_requests(struct mqtt_request_t **tail)
 static void
 mqtt_init_requests(struct mqtt_request_t *r_objs)
 {
-  LWIP_ASSERT("mqtt_init_requests: r_objs != NULL", r_objs != NULL);
   u8_t n;
+  LWIP_ASSERT("mqtt_init_requests: r_objs != NULL", r_objs != NULL);
   for(n = 0; n < MQTT_REQ_MAX_IN_FLIGHT; n++) {
     /* Item pointing to itself indicates unused */
     r_objs[n].next = &r_objs[n];
@@ -442,7 +444,6 @@ mqtt_output_append_u8(struct mqtt_ringbuf_t *rb, u8_t value)
 static
 void mqtt_output_append_u16(struct mqtt_ringbuf_t *rb, u16_t value)
 {
-
   mqtt_ringbuf_put(rb, value >> 8);
   mqtt_ringbuf_put(rb, value & 0xff);
 }
@@ -459,9 +460,9 @@ mqtt_output_append_buf(struct mqtt_ringbuf_t *rb, const void *data, u16_t length
 static void
 mqtt_output_append_string(struct mqtt_ringbuf_t *rb, const char *str, u16_t length)
 {
+  u16_t n;
   mqtt_ringbuf_put(rb, length >> 8);
   mqtt_ringbuf_put(rb, length & 0xff);
-  u16_t n;
   for(n=0; n < length; n++) {
     mqtt_ringbuf_put(rb, str[n]);
   }
@@ -481,7 +482,6 @@ static void
 mqtt_output_append_fixed_header(struct mqtt_ringbuf_t *rb, u8_t msg_type, u8_t dup,
                  u8_t qos, u8_t retain, u16_t r_length)
 {
-
   /* Start with control byte */
   mqtt_output_append_u8(rb, (((msg_type & 0x0f) << 4) | ((dup & 1) << 3) | ((qos & 3) << 1) | (retain & 1)));
   /* Encode remaining length field */
@@ -501,11 +501,11 @@ mqtt_output_append_fixed_header(struct mqtt_ringbuf_t *rb, u8_t msg_type, u8_t d
 static u8_t
 mqtt_output_check_space(struct mqtt_ringbuf_t *rb, u16_t r_length)
 {
-  LWIP_ASSERT("mqtt_output_check_space: rb != NULL", rb != NULL);
-
   /* Start with length of type byte + remaining length */
   u16_t total_len = 1 + r_length;
 
+  LWIP_ASSERT("mqtt_output_check_space: rb != NULL", rb != NULL);
+
  /* Calculate number of required bytes to contain the remaining bytes field and add to total*/
   do {
     total_len++;
@@ -670,7 +670,7 @@ mqtt_message_received(mqtt_client_t *client, u8_t fixed_hdr_idx, u16_t length, u
   if(pkt_type == MQTT_MSG_TYPE_CONNACK) {
     if(client->conn_state == MQTT_CONNECTING) {
       /* Get result code from CONNACK */
-      res = var_hdr_payload[1];
+      res = (mqtt_connection_status_t)var_hdr_payload[1];
       LWIP_DEBUGF(MQTT_DEBUG_TRACE,("mqtt_message_received: Connect response code %d\n", res));
       if(res == MQTT_CONNECT_ACCEPTED) {
         /* Reset cyclic_tick when changing to connected state */
@@ -918,9 +918,10 @@ mqtt_tcp_recv_cb(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
 static err_t
 mqtt_tcp_sent_cb(void *arg, struct tcp_pcb *tpcb, u16_t len)
 {
+  mqtt_client_t *client = (mqtt_client_t *)arg;
+
   LWIP_UNUSED_ARG(tpcb);
   LWIP_UNUSED_ARG(len);
-  mqtt_client_t *client = (mqtt_client_t *)arg;
 
   if(client->conn_state == MQTT_CONNECTED) {
 
@@ -984,11 +985,12 @@ mqtt_tcp_poll_cb(void *arg, struct tcp_pcb *tpcb)
 static err_t
 mqtt_tcp_connect_cb(void *arg, struct tcp_pcb *tpcb, err_t err)
 {
+  mqtt_client_t* client = (mqtt_client_t *)arg;
+
   if(err != ERR_OK) {
     LWIP_DEBUGF(MQTT_DEBUG_WARN,("mqtt_tcp_connect_cb: TCP connect error %d\n", err));
     return err;
   }
-  mqtt_client_t* client = (mqtt_client_t *)arg;
 
   /* Initiate receiver state */
   client->msg_idx = 0;
@@ -1025,6 +1027,7 @@ mqtt_tcp_connect_cb(void *arg, struct tcp_pcb *tpcb, err_t err)
  * @param payload Data to publish (NULL is allowed)
  * @param payload_length: Length of payload (0 is allowed)
  * @param qos Quality of service, 0 1 or 2
+ * @param retain MQTT retain flag
  * @param cb Callback to call when publish is complete or has timed out
  * @param arg User supplied argument to publish callback
  * @return ERR_OK if successful
@@ -1035,17 +1038,17 @@ err_t
 mqtt_publish(mqtt_client_t *client, const char *topic, const void *payload, u16_t payload_length, u8_t qos, u8_t retain,
              mqtt_request_cb_t cb, void *arg)
 {
+  struct mqtt_request_t *r;
+  u16_t pkt_id;
+  u16_t topic_len = strlen(topic);
+  u16_t remaining_length = 2 + topic_len + payload_length;
+
   LWIP_ASSERT("mqtt_publish: client != NULL", client);
   LWIP_ASSERT("mqtt_publish: topic != NULL", topic);
   LWIP_ERROR("mqtt_publish: TCP disconnected", (client->conn_state != TCP_DISCONNECTED), return ERR_CONN);
 
   LWIP_DEBUGF(MQTT_DEBUG_TRACE,("mqtt_publish: Publish with payload length %d to topic \"%s\"\n", payload_length, topic));
 
-  struct mqtt_request_t *r;
-  u16_t pkt_id;
-  u16_t topic_len = strlen(topic);
-  u16_t remaining_length = 2 + topic_len + payload_length;
-
   if(qos > 0) {
     remaining_length += 2;
     /* Generate pkt_id id for QoS1 and 2 */
@@ -1099,6 +1102,13 @@ mqtt_publish(mqtt_client_t *client, const char *topic, const void *payload, u16_
 err_t
 mqtt_sub_unsub(mqtt_client_t *client, const char *topic, u8_t qos, mqtt_request_cb_t cb, void *arg, u8_t sub)
 {
+  u16_t topic_len = strlen(topic);
+  /* Topic string, pkt_id, qos for subscribe */
+  u16_t remaining_length =  topic_len + 2 + 2 + (sub != 0);
+
+  u16_t pkt_id = msg_generate_packet_id(client);
+  struct mqtt_request_t *r = mqtt_create_request(client->req_list, pkt_id, cb, arg);
+
   LWIP_ASSERT("mqtt_sub_unsub: client != NULL", client);
   LWIP_ASSERT("mqtt_sub_unsub: topic != NULL", topic);
   LWIP_ASSERT("mqtt_sub_unsub: qos < 3", qos < 3);
@@ -1107,12 +1117,6 @@ mqtt_sub_unsub(mqtt_client_t *client, const char *topic, u8_t qos, mqtt_request_
     return ERR_CONN;
   }
 
-  u16_t topic_len = strlen(topic);
-  /* Topic string, pkt_id, qos for subscribe */
-  u16_t remaining_length =  topic_len + 2 + 2 + (sub != 0);
-
-  u16_t pkt_id = msg_generate_packet_id(client);
-  struct mqtt_request_t *r = mqtt_create_request(client->req_list, pkt_id, cb, arg);
   if(r == NULL) {
     return ERR_MEM;
   }
@@ -1159,7 +1163,6 @@ mqtt_set_inpub_callback(mqtt_client_t *client, mqtt_incoming_publish_cb_t pub_cb
 
 /**
  * Create a new MQTT client instance
- * @param client MQTT client
  * @return Pointer to instance on success, NULL otherwise
  */
 mqtt_client_t *
@@ -1186,6 +1189,12 @@ err_t
 mqtt_client_connect(mqtt_client_t *client, const char *host, mqtt_connection_cb_t cb, void *arg,
                     const struct mqtt_connect_client_info_t *client_info)
 {
+  err_t err;
+  ip_addr_t ip_addr;
+  u16_t port = 1883;
+  /* Length is the sum of 2+"MQTT", protocol level, flags and keep alive */
+  u16_t remaining_length = 2 + 4 + 1 + 1 + 2;
+  u8_t flags = 0, will_topic_len = 0, will_msg_len = 0;
 
   LWIP_ASSERT("mqtt_client_connect: client != NULL", client != NULL);
   LWIP_ASSERT("mqtt_client_connect: host != NULL", host != NULL);
@@ -1196,9 +1205,6 @@ mqtt_client_connect(mqtt_client_t *client, const char *host, mqtt_connection_cb_
     LWIP_DEBUGF(MQTT_DEBUG_WARN,("mqtt_client_connect: Already connected\n"));
     return ERR_ISCONN;
   }
-  err_t err;
-  ip_addr_t ip_addr;
-  u16_t port = 1883;
 
   if(ipaddr_aton(host, &ip_addr) == 0) {
     LWIP_DEBUGF(MQTT_DEBUG_WARN,("mqtt_client_connect: Illegal hostname: %s\n", host));
@@ -1212,10 +1218,6 @@ mqtt_client_connect(mqtt_client_t *client, const char *host, mqtt_connection_cb_
   mqtt_init_requests(client->req_list);
 
   /* Build connect message */
-  /* Length is the sum of 2+"MQTT", protocol level, flags and keep alive */
-  u16_t remaining_length = 2 + 4 + 1 + 1 + 2;
-  u8_t flags = 0, will_topic_len = 0, will_msg_len = 0;
-
   if(client_info->will_topic != NULL && client_info->will_msg != NULL) {
     flags |= MQTT_CONNECT_FLAG_WILL;
     flags |= (client_info->will_qos & 3) << 3;
@@ -1284,7 +1286,6 @@ tcp_fail:
   tcp_abort(client->conn);
   client->conn = NULL;
   return err;
-
 }
 
 
@@ -1300,7 +1301,7 @@ mqtt_disconnect(mqtt_client_t *client)
   if(client->conn_state != TCP_DISCONNECTED) {
     /* Set conn_state before calling mqtt_close to prevent callback from being called */
     client->conn_state = TCP_DISCONNECTED;
-    mqtt_close(client, 0);
+    mqtt_close(client, (mqtt_connection_status_t)0);
   }
 }
 
diff --git a/src/include/lwip/apps/mqtt.h b/src/include/lwip/apps/mqtt.h
index 3b27bb08..e5cd3660 100644
--- a/src/include/lwip/apps/mqtt.h
+++ b/src/include/lwip/apps/mqtt.h
@@ -44,6 +44,10 @@
 extern "C" {
 #endif
 
+/** @ingroup mqtt
+ * @{
+ */
+
 /**
  * Output ring-buffer size, must be able to fit largest outgoing publish message topic+payloads
  */
@@ -173,39 +177,42 @@ struct mqtt_request_t
   u16_t timeout_diff;
 };
 
+/** Ring buffer */
+struct mqtt_ringbuf_t {
+  u16_t put;
+  u16_t get;
+  u8_t buf[MQTT_OUTPUT_RINGBUF_SIZE];
+};
+
 /** MQTT client */
 struct mqtt_client_t
 {
-	/** Timers and timeouts */
-	u16_t cyclic_tick;
+  /** Timers and timeouts */
+  u16_t cyclic_tick;
   u16_t keep_alive;
   u16_t server_watchdog;
-	/** Packet identifier generator*/
-	u16_t pkt_id_seq;
+  /** Packet identifier generator*/
+  u16_t pkt_id_seq;
   /** Packet identifier of pending incoming publish */
   u16_t inpub_pkt_id;
   /** Connection state */
   u8_t conn_state;
   struct tcp_pcb *conn;
-	/** Connection callback */
-	void *connect_arg;
-	mqtt_connection_cb_t connect_cb;
+  /** Connection callback */
+  void *connect_arg;
+  mqtt_connection_cb_t connect_cb;
   /** Pending requests to server */
   struct mqtt_request_t *pend_req_queue;
   struct mqtt_request_t req_list[MQTT_REQ_MAX_IN_FLIGHT];
-	void *inpub_arg;
-	/** Incoming data callback */
-	mqtt_incoming_data_cb_t data_cb;
+  void *inpub_arg;
+  /** Incoming data callback */
+  mqtt_incoming_data_cb_t data_cb;
   mqtt_incoming_publish_cb_t pub_cb;
   /** Input */
   u32_t msg_idx;
   u8_t rx_buffer[MQTT_VAR_HEADER_BUFFER_LEN];
-	/** Output ring-buffer */
-	struct mqtt_ringbuf_t {
-    u16_t put;
-    u16_t get;
-    u8_t buf[MQTT_OUTPUT_RINGBUF_SIZE];
-  } output;
+  /** Output ring-buffer */
+  struct mqtt_ringbuf_t output;
 };
 
 
@@ -239,6 +246,10 @@ err_t mqtt_sub_unsub(mqtt_client_t *client, const char *topic, u8_t qos, mqtt_re
 err_t mqtt_publish(mqtt_client_t *client, const char *topic, const void *payload, u16_t payload_length, u8_t qos, u8_t retain,
                                     mqtt_request_cb_t cb, void *arg);
 
+/**
+ * @}
+ */
+
 #ifdef	__cplusplus
 }
 #endif