diff --git a/Adafruit_MQTT.cpp b/Adafruit_MQTT.cpp
index ce41243..8d729ec 100644
--- a/Adafruit_MQTT.cpp
+++ b/Adafruit_MQTT.cpp
@@ -1,7 +1,7 @@
 #include "Adafruit_MQTT.h"
 
 
-Adafruit_MQTT::Adafruit_MQTT(char *server, uint16_t port, char *user, char *key) {
+Adafruit_MQTT::Adafruit_MQTT(char *server, uint16_t port, char *user, char *key, char *cid) {
   strncpy(servername, server, SERVERNAME_SIZE);
   servername[SERVERNAME_SIZE-1] = 0;
   portnum = port;
@@ -9,7 +9,9 @@ Adafruit_MQTT::Adafruit_MQTT(char *server, uint16_t port, char *user, char *key)
   strncpy(username, user, USERNAME_SIZE);
   username[USERNAME_SIZE-1] = 0;
   strncpy(userkey, key, KEY_SIZE);
-  userkey[KEY_SIZE-1] = 0; 
+  userkey[KEY_SIZE-1] = 0;
+  strncpy(clientid, cid, CLIENTID_SIZE);
+  userkey[CLIENTID_SIZE-1] = 0;
 
   errno = 0;
 }
@@ -24,9 +26,9 @@ uint8_t Adafruit_MQTT::connectPacket(uint8_t *packet) {
   // fill in packet[1] last
 
   p[0] = 0;
-  p[1] = 6; // (strlen(MQIdsp)
+  p[1] = 6; // (strlen(MQIsdp)
   p+=2;
-  memcpy(p,"MQIdsp", 6);
+  memcpy(p,"MQIsdp", 6);
   p+=6;
 
   p[0] = MQTT_PROTOCOL_LEVEL;
@@ -45,15 +47,21 @@ uint8_t Adafruit_MQTT::connectPacket(uint8_t *packet) {
   p[0] = MQTT_CONN_KEEPALIVE & 0xFF;
   p++;
 
+  uint16_t len = strlen(clientid);
+  p[0] = len >> 8; p++;
+  p[0] = len & 0xFF; p++;
+  memcpy(p, clientid, len);
+  p+=len;
+
   if (username[0] != 0) {
-    uint16_t len = strlen(username);
+    len = strlen(username);
     p[0] = len >> 8; p++;
     p[0] = len & 0xFF; p++;
     memcpy(p, username, len);
     p+=len;
   }
   if (userkey[0] != 0) {
-    uint16_t len = strlen(userkey);
+    len = strlen(userkey);
     p[0] = len >> 8; p++;
     p[0] = len & 0xFF; p++;
     memcpy(p, userkey, len);
diff --git a/Adafruit_MQTT.h b/Adafruit_MQTT.h
index 398f2d5..59a44f1 100644
--- a/Adafruit_MQTT.h
+++ b/Adafruit_MQTT.h
@@ -19,7 +19,8 @@
 #define SERVERNAME_SIZE  25
 #define USERNAME_SIZE  25
 #define KEY_SIZE  41
-#define FEEDNAME_SIZE  65
+#define FEEDNAME_SIZE  25
+#define CLIENTID_SIZE 23
 
 #define CONNECT_TIMEOUT_MS 3000
 #define PUBLISH_TIMEOUT_MS 500
@@ -47,6 +48,7 @@ class Adafruit_MQTT {
   char servername[SERVERNAME_SIZE];
   uint32_t serverip;
   int16_t portnum;
+  char clientid[CLIENTID_SIZE];
   char username[USERNAME_SIZE];
   char userkey[KEY_SIZE];