diff --git a/examples/mqtt_client/mqtt_client.c b/examples/mqtt_client/mqtt_client.c
index 704ed9eaced0db90b2c02a51b20dcffa887c532d..4be13b49536f9368f4ca4533147a592099a0761c 100644
--- a/examples/mqtt_client/mqtt_client.c
+++ b/examples/mqtt_client/mqtt_client.c
@@ -17,12 +17,14 @@
 
 #include "mongoose.h"
 
-struct mg_mqtt_topic_expression topic_expressions[] = {
-  {"/stuff", 0}
-};
+static const char *s_address = "localhost:1883";
+static const char *s_user_name = NULL;
+static const char *s_password = NULL;
+
+struct mg_mqtt_topic_expression topic_expressions[] = {{"/stuff", 0}};
 
 static void ev_handler(struct mg_connection *nc, int ev, void *p) {
-  struct mg_mqtt_message *msg = (struct mg_mqtt_message *)p;
+  struct mg_mqtt_message *msg = (struct mg_mqtt_message *) p;
   (void) nc;
 
 #if 0
@@ -31,17 +33,25 @@ static void ev_handler(struct mg_connection *nc, int ev, void *p) {
 #endif
 
   switch (ev) {
-    case MG_EV_CONNECT:
+    case MG_EV_CONNECT: {
+      struct mg_send_mqtt_handshake_opts opts;
+      memset(&opts, 0, sizeof(opts));
+      opts.user_name = s_user_name;
+      opts.password = s_password;
+
       mg_set_protocol_mqtt(nc);
-      mg_send_mqtt_handshake(nc, "dummy");
+      mg_send_mqtt_handshake_opt(nc, "dummy", opts);
       break;
+    }
     case MG_EV_MQTT_CONNACK:
       if (msg->connack_ret_code != MG_EV_MQTT_CONNACK_ACCEPTED) {
         printf("Got mqtt connection error: %d\n", msg->connack_ret_code);
         exit(1);
       }
       printf("Subscribing to '/stuff'\n");
-      mg_mqtt_subscribe(nc, topic_expressions, sizeof(topic_expressions)/sizeof(*topic_expressions), 42);
+      mg_mqtt_subscribe(nc, topic_expressions,
+                        sizeof(topic_expressions) / sizeof(*topic_expressions),
+                        42);
       break;
     case MG_EV_MQTT_PUBACK:
       printf("Message publishing acknowledged (msg_id: %d)\n", msg->message_id);
@@ -49,38 +59,53 @@ static void ev_handler(struct mg_connection *nc, int ev, void *p) {
     case MG_EV_MQTT_SUBACK:
       printf("Subscription acknowledged, forwarding to '/test'\n");
       break;
-    case MG_EV_MQTT_PUBLISH:
-      {
+    case MG_EV_MQTT_PUBLISH: {
 #if 0
         char hex[1024] = {0};
         mg_hexdump(nc->recv_mbuf.buf, msg->payload.len, hex, sizeof(hex));
         printf("Got incoming message %s:\n%s", msg->topic, hex);
 #else
-        printf("Got incoming message %s: %.*s\n", msg->topic, (int)msg->payload.len, msg->payload.p);
+      printf("Got incoming message %s: %.*s\n", msg->topic,
+             (int) msg->payload.len, msg->payload.p);
 #endif
 
-        printf("Forwarding to /test\n");
-        mg_mqtt_publish(nc, "/test", 65, MG_MQTT_QOS(0), msg->payload.p, msg->payload.len);
-      }
+      printf("Forwarding to /test\n");
+      mg_mqtt_publish(nc, "/test", 65, MG_MQTT_QOS(0), msg->payload.p,
+                      msg->payload.len);
       break;
+    }
     case MG_EV_CLOSE:
       printf("Connection closed\n");
       exit(1);
   }
 }
 
-int main(void) {
+int main(int argc, char **argv) {
   struct mg_mgr mgr;
-  const char *address = "localhost:1883";
+  int i;
 
   mg_mgr_init(&mgr, NULL);
 
-  if (mg_connect(&mgr, address, ev_handler) == NULL) {
-    fprintf(stderr, "mg_connect(%s) failed\n", address);
+  /* Parse command line arguments */
+  for (i = 1; i < argc; i++) {
+    if (strcmp(argv[i], "-h") == 0) {
+      s_address = argv[i + 1];
+      i++;
+    } else if (strcmp(argv[i], "-u") == 0) {
+      s_user_name = argv[i + 1];
+      i++;
+    } else if (strcmp(argv[i], "-p") == 0) {
+      s_password = argv[i + 1];
+      i++;
+    }
+  }
+
+  if (mg_connect(&mgr, s_address, ev_handler) == NULL) {
+    fprintf(stderr, "mg_connect(%s) failed\n", s_address);
     exit(EXIT_FAILURE);
   }
 
-  for(;;) {
+  for (;;) {
     mg_mgr_poll(&mgr, 1000);
   }
 }
diff --git a/mongoose.c b/mongoose.c
index 264cc424c912d0dad134ceb9b07436ba2b2de60b..241298455aa95c8d44cda25231882542f4709ce5 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -8399,6 +8399,8 @@ int mg_rpc_parse_reply(const char *buf, int len, struct json_token *toks,
 
 #ifndef MG_DISABLE_MQTT
 
+#include <string.h>
+
 /* Amalgamated: #include "mongoose/src/internal.h" */
 /* Amalgamated: #include "mongoose/src/mqtt.h" */
 
@@ -8509,7 +8511,7 @@ void mg_send_mqtt_handshake_opt(struct mg_connection *nc, const char *client_id,
   uint8_t header = MG_MQTT_CMD_CONNECT << 4;
   uint8_t rem_len;
   uint16_t keep_alive;
-  uint16_t client_id_len;
+  uint16_t len;
 
   /*
    * 9: version_header(len, magic_string, version_number), 1: flags, 2:
@@ -8518,6 +8520,15 @@ void mg_send_mqtt_handshake_opt(struct mg_connection *nc, const char *client_id,
    */
   rem_len = 9 + 1 + 2 + 2 + strlen(client_id);
 
+  if (opts.user_name != NULL) {
+    opts.flags |= MG_MQTT_HAS_USER_NAME;
+    rem_len += strlen(opts.user_name) + 2;
+  }
+  if (opts.password != NULL) {
+    opts.flags |= MG_MQTT_HAS_PASSWORD;
+    rem_len += strlen(opts.password) + 2;
+  }
+
   mg_send(nc, &header, 1);
   mg_send(nc, &rem_len, 1);
   mg_send(nc, "\00\06MQIsdp\03", 9);
@@ -8529,9 +8540,20 @@ void mg_send_mqtt_handshake_opt(struct mg_connection *nc, const char *client_id,
   keep_alive = htons(opts.keep_alive);
   mg_send(nc, &keep_alive, 2);
 
-  client_id_len = htons(strlen(client_id));
-  mg_send(nc, &client_id_len, 2);
+  len = htons(strlen(client_id));
+  mg_send(nc, &len, 2);
   mg_send(nc, client_id, strlen(client_id));
+
+  if (opts.flags & MG_MQTT_HAS_USER_NAME) {
+    len = htons(strlen(opts.user_name));
+    mg_send(nc, &len, 2);
+    mg_send(nc, opts.user_name, strlen(opts.user_name));
+  }
+  if (opts.flags & MG_MQTT_HAS_PASSWORD) {
+    len = htons(strlen(opts.password));
+    mg_send(nc, &len, 2);
+    mg_send(nc, opts.password, strlen(opts.password));
+  }
 }
 
 static void mg_mqtt_prepend_header(struct mg_connection *nc, uint8_t cmd,