diff --git a/Adafruit_MQTT.cpp b/Adafruit_MQTT.cpp
index 5d98279..5558a65 100644
--- a/Adafruit_MQTT.cpp
+++ b/Adafruit_MQTT.cpp
@@ -38,6 +38,7 @@ void printBuffer(uint8_t *buffer, uint8_t len) {
   DEBUG_PRINTER.println();
 }
 
+/* Not used now, but might be useful in the future
 static uint8_t *stringprint(uint8_t *p, char *s) {
   uint16_t len = strlen(s);
   p[0] = len >> 8; p++;
@@ -45,6 +46,7 @@ static uint8_t *stringprint(uint8_t *p, char *s) {
   memcpy(p, s, len);
   return p+len;
 }
+*/
 
 static uint8_t *stringprint_P(uint8_t *p, const char *s, uint16_t maxlen=0) {
   // If maxlen is specified (has a non-zero value) then use it as the maximum
@@ -81,6 +83,20 @@ Adafruit_MQTT::Adafruit_MQTT(const char *server, uint16_t port, const char *cid,
   }
 }
 
+Adafruit_MQTT::Adafruit_MQTT(const __FlashStringHelper *server, uint16_t port, const __FlashStringHelper *cid,
+                             const __FlashStringHelper *user, const __FlashStringHelper *pass) {
+  servername = (const char *)server;
+  portnum = port;
+  clientid = (const char *)cid;
+  username = (const char *)user;
+  password = (const char *)pass;
+
+  for (uint8_t i=0; i<MAXSUBSCRIPTIONS; i++) {
+    subscriptions[i] = 0;
+  }
+}
+
+
 /*
 Adafruit_MQTT::Adafruit_MQTT(char *server, uint16_t port, char *cid, char *user, char *pass) {
   strncpy(servername, server, SERVERNAME_SIZE);
@@ -140,7 +156,20 @@ int8_t Adafruit_MQTT::connect() {
   return 0;
 }
 
-bool Adafruit_MQTT::publish(const char *topic, char *data, uint8_t qos) {
+const __FlashStringHelper* Adafruit_MQTT::connectErrorString(int8_t code) {
+   switch (code) {
+      case 1: return F("Wrong protocol");
+      case 2: return F("ID rejected");
+      case 3: return F("Server unavail");
+      case 4: return F("Bad user/pass");
+      case 5: return F("Not authed");
+      case 6: return F("Failed to subscribe");
+      case -1: return F("Connection failed");
+      default: return F("Unknown error");
+   }
+}
+
+bool Adafruit_MQTT::publish(const char *topic, const char *data, uint8_t qos) {
   // Construct and send publish packet.
   uint8_t len = publishPacket(buffer, topic, data, qos);
   if (!sendPacket(buffer, len))
@@ -163,22 +192,21 @@ bool Adafruit_MQTT::subscribe(Adafruit_MQTT_Subscribe *sub) {
   for (i=0; i<MAXSUBSCRIPTIONS; i++) {
     if (subscriptions[i] == sub) {
       DEBUG_PRINTLN(F("Already subscribed"));
-      break;
+      return true;
     }
   }
   if (i==MAXSUBSCRIPTIONS) { // add to subscriptionlist
-      for (i=0; i<MAXSUBSCRIPTIONS; i++) {
-  if (subscriptions[i] == 0) {
-    DEBUG_PRINT(F("Added sub ")); DEBUG_PRINTLN(i);
-    subscriptions[i] = sub;
-    break;
-  }
-      } 
-  }
-  if (i==MAXSUBSCRIPTIONS) {
-    DEBUG_PRINTLN(F("no more subscription space :("));
-    return false;
+    for (i=0; i<MAXSUBSCRIPTIONS; i++) {
+      if (subscriptions[i] == 0) {
+        DEBUG_PRINT(F("Added sub ")); DEBUG_PRINTLN(i);
+        subscriptions[i] = sub;
+        return true;
+      }
+    }
   }
+
+  DEBUG_PRINTLN(F("no more subscription space :("));
+  return false;
 }
 
 Adafruit_MQTT_Subscribe *Adafruit_MQTT::readSubscription(int16_t timeout) {
@@ -220,6 +248,7 @@ Adafruit_MQTT_Subscribe *Adafruit_MQTT::readSubscription(int16_t timeout) {
   }
   // extract out just the data, into the subscription object itself
   memcpy(subscriptions[i]->lastread, buffer+4+topiclen, datalen);
+  subscriptions[i]->datalen = datalen;
   DEBUG_PRINT(F("Data len: ")); DEBUG_PRINTLN(datalen);
   DEBUG_PRINT(F("Data: ")); DEBUG_PRINTLN((char *)subscriptions[i]->lastread);
 
@@ -294,7 +323,7 @@ uint8_t Adafruit_MQTT::connectPacket(uint8_t *packet) {
 }
 
 uint8_t Adafruit_MQTT::publishPacket(uint8_t *packet, const char *topic, 
-                                     char *data, uint8_t qos) {
+                                     const char *data, uint8_t qos) {
   uint8_t *p = packet;
   uint16_t len;
 
@@ -357,6 +386,13 @@ Adafruit_MQTT_Publish::Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver,
   qos = q;
 }
 
+Adafruit_MQTT_Publish::Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver,
+                                             const __FlashStringHelper *feed, uint8_t q) {
+  mqtt = mqttserver;
+  topic = (const char *)feed;
+  qos = q;
+}
+
 bool Adafruit_MQTT_Publish::publish(int32_t i) {
   char payload[18];
   itoa(i, payload, 10);
@@ -375,7 +411,7 @@ bool Adafruit_MQTT_Publish::publish(uint32_t i) {
   return mqtt->publish(topic, payload, qos);
 }
 
-bool Adafruit_MQTT_Publish::publish(char *payload) {
+bool Adafruit_MQTT_Publish::publish(const char *payload) {
   return mqtt->publish(topic, payload, qos);
 }
 
@@ -388,3 +424,10 @@ Adafruit_MQTT_Subscribe::Adafruit_MQTT_Subscribe(Adafruit_MQTT *mqttserver,
   topic = feed;
   qos = q;
 }
+
+Adafruit_MQTT_Subscribe::Adafruit_MQTT_Subscribe(Adafruit_MQTT *mqttserver,
+                                                 const __FlashStringHelper *feed, uint8_t q) {
+  mqtt = mqttserver;
+  topic = (const char *)feed;
+  qos = q;
+}
diff --git a/Adafruit_MQTT.h b/Adafruit_MQTT.h
index c5c76aa..e18110e 100644
--- a/Adafruit_MQTT.h
+++ b/Adafruit_MQTT.h
@@ -94,6 +94,8 @@ class Adafruit_MQTT {
  public:
   Adafruit_MQTT(const char *server, uint16_t port, const char *cid,
                 const char *user, const char *pass);
+  Adafruit_MQTT(const __FlashStringHelper *server, uint16_t port, const __FlashStringHelper *cid,
+                const __FlashStringHelper *user, const __FlashStringHelper *pass);
   virtual ~Adafruit_MQTT() {}
 
   // Connect to the MQTT server.  Returns 0 on success, otherwise an error code
@@ -105,8 +107,16 @@ class Adafruit_MQTT {
   //    4 = Bad username or password
   //    5 = Not authenticated
   //    6 = Failed to subscribe
+  // Use connectErrorString() to get a printable string version of the
+  // error.
   int8_t connect();
 
+  // Return a printable string version of the error code returned by
+  // connect(). This returns a __FlashStringHelper*, which points to a
+  // string stored in flash, but can be directly passed to e.g.
+  // Serial.println without any further processing.
+  const __FlashStringHelper* connectErrorString(int8_t code);
+
   // Disconnect from the MQTT server.  Returns true if disconnected, false
   // otherwise.
   virtual bool disconnect() = 0;  // Subclasses need to fill this in!
@@ -116,10 +126,17 @@ class Adafruit_MQTT {
 
   // Publish a message to a topic using the specified QoS level.  Returns true
   // if the message was published, false otherwise.
-  bool publish(const char *topic, char *payload, uint8_t qos);
+  // The topic must be stored in PROGMEM. It can either be a
+  // char*, or a __FlashStringHelper* (the result of the F() macro).
+  bool publish(const char *topic, const char *payload, uint8_t qos = 0);
+  bool publish(const __FlashStringHelper *topic, const char *payload, uint8_t qos = 0) {
+    return publish((const char *)topic, payload, qos);
+  }
 
   // Add a subscription to receive messages for a topic.  Returns true if the
-  // subscription could be added, false otherwise.
+  // subscription could be added or was already present, false otherwise.
+  // Must be called before connect(), subscribing after the connection
+  // is made is not currently supported.
   bool subscribe(Adafruit_MQTT_Subscribe *sub);
 
   // Check if any subscriptions have new messages.  Will return a reference to
@@ -161,7 +178,7 @@ class Adafruit_MQTT {
 
   // Functions to generate MQTT packets.
   uint8_t connectPacket(uint8_t *packet);
-  uint8_t publishPacket(uint8_t *packet, const char *topic, char *payload, uint8_t qos);
+  uint8_t publishPacket(uint8_t *packet, const char *topic, const char *payload, uint8_t qos);
   uint8_t subscribePacket(uint8_t *packet, const char *topic, uint8_t qos);
   uint8_t pingPacket(uint8_t *packet);
 };
@@ -170,8 +187,9 @@ class Adafruit_MQTT {
 class Adafruit_MQTT_Publish {
  public:
   Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver, const char *feed, uint8_t qos = 0);
+  Adafruit_MQTT_Publish(Adafruit_MQTT *mqttserver, const __FlashStringHelper *feed, uint8_t qos = 0);
 
-  bool publish(char *s);
+  bool publish(const char *s);
   bool publish(double f, uint8_t precision=2);  // Precision controls the minimum number of digits after decimal.
                                                 // This might be ignored and a higher precision value sent.
   bool publish(int32_t i);
@@ -186,13 +204,17 @@ private:
 class Adafruit_MQTT_Subscribe {
  public:
   Adafruit_MQTT_Subscribe(Adafruit_MQTT *mqttserver, const char *feedname, uint8_t q=0);
+  Adafruit_MQTT_Subscribe(Adafruit_MQTT *mqttserver, const __FlashStringHelper *feedname, uint8_t q=0);
 
   bool setCallback(void (*callback)(char *));
 
   const char *topic;
   uint8_t qos;
 
-  uint8_t * lastread[SUBSCRIPTIONDATALEN];
+  uint8_t lastread[SUBSCRIPTIONDATALEN];
+  // Number valid bytes in lastread. Limited to SUBSCRIPTIONDATALEN-1 to
+  // ensure nul terminating lastread.
+  uint8_t datalen;
  private:
   Adafruit_MQTT *mqtt;
 };
diff --git a/examples/mqtt_cc3k/mqtt_cc3k.ino b/examples/mqtt_cc3k/mqtt_cc3k.ino
index d2490f4..e9731a2 100644
--- a/examples/mqtt_cc3k/mqtt_cc3k.ino
+++ b/examples/mqtt_cc3k/mqtt_cc3k.ino
@@ -121,7 +121,7 @@ void loop() {
 
   // this is our 'wait for incoming subscription packets' busy subloop
   Adafruit_MQTT_Subscribe *subscription;
-  while (subscription = mqtt.readSubscription(1000)) {
+  while ((subscription = mqtt.readSubscription(1000))) {
     if (subscription == &onoffbutton) {
       Serial.print(F("Got: "));
       Serial.println((char *)onoffbutton.lastread);
@@ -152,18 +152,9 @@ void MQTT_connect() {
   Serial.print("Connecting to MQTT... ");
 
   while ((ret = mqtt.connect()) != 0) { // connect will return 0 for connected
-       switch (ret) {
-          case 1: Serial.println("Wrong protocol"); break;
-          case 2: Serial.println("ID rejected"); break;
-          case 3: Serial.println("Server unavailable"); break;
-          case 4: Serial.println("Bad user/password"); break;
-          case 5: Serial.println("Not authenticated"); break;
-          case 6: Serial.println("Failed to subscribe"); break;
-          default:
-            Serial.println(F("Connection failed"));
+       Serial.println(mqtt.connectErrorString(ret));
+       if (ret < 0)
             CC3000connect(WLAN_SSID, WLAN_PASS, WLAN_SECURITY);  // y0w, lets connect to wifi again
-            break;
-       }
        Serial.println("Retrying MQTT connection in 5 seconds...");
        mqtt.disconnect();
        delay(5000);  // wait 5 seconds
diff --git a/examples/mqtt_esp8266/mqtt_esp8266.ino b/examples/mqtt_esp8266/mqtt_esp8266.ino
index 5a7d217..528f002 100644
--- a/examples/mqtt_esp8266/mqtt_esp8266.ino
+++ b/examples/mqtt_esp8266/mqtt_esp8266.ino
@@ -104,7 +104,7 @@ void loop() {
 
   // this is our 'wait for incoming subscription packets' busy subloop
   Adafruit_MQTT_Subscribe *subscription;
-  while (subscription = mqtt.readSubscription(1000)) {
+  while ((subscription = mqtt.readSubscription(1000))) {
     if (subscription == &onoffbutton) {
       Serial.print(F("Got: "));
       Serial.println((char *)onoffbutton.lastread);
@@ -137,17 +137,7 @@ void MQTT_connect() {
   Serial.print("Connecting to MQTT... ");
 
   while ((ret = mqtt.connect()) != 0) { // connect will return 0 for connected
-       switch (ret) {
-          case 1: Serial.println("Wrong protocol"); break;
-          case 2: Serial.println("ID rejected"); break;
-          case 3: Serial.println("Server unavailable"); break;
-          case 4: Serial.println("Bad user/password"); break;
-          case 5: Serial.println("Not authenticated"); break;
-          case 6: Serial.println("Failed to subscribe"); break;
-          default: Serial.print("Couldn't connect to server, code: ");
-                   Serial.println(ret);
-                   break;
-       }
+       Serial.println(mqtt.connectErrorString(ret));
        Serial.println("Retrying MQTT connection in 5 seconds...");
        mqtt.disconnect();
        delay(5000);  // wait 5 seconds
diff --git a/examples/mqtt_fona/mqtt_fona.ino b/examples/mqtt_fona/mqtt_fona.ino
index fd95690..e14dcf6 100644
--- a/examples/mqtt_fona/mqtt_fona.ino
+++ b/examples/mqtt_fona/mqtt_fona.ino
@@ -122,18 +122,7 @@ void loop() {
     Serial.println(F("Connecting to MQTT..."));
     int8_t ret, retries = 5;
     while (retries && (ret = mqtt.connect()) != 0) {
-       switch (ret) {
-          case 1: Serial.println(F("Wrong protocol")); break;
-          case 2: Serial.println(F("ID rejected")); break;
-          case 3: Serial.println(F("Server unavail")); break;
-          case 4: Serial.println(F("Bad user/pass")); break;
-          case 5: Serial.println(F("Not authed")); break;
-          case 6: Serial.println(F("Failed to subscribe")); break;
-          default: {
-            Serial.println(F("Connection failed"));
-            break;
-          }
-       }
+       Serial.println(mqtt.connectErrorString(ret));
        Serial.println(F("Retrying MQTT connection"));
        retries--;
        if (retries == 0) halt("Resetting system");
@@ -155,7 +144,7 @@ void loop() {
 
   // this is our 'wait for incoming subscription packets' busy subloop
   Adafruit_MQTT_Subscribe *subscription;
-  while (subscription = mqtt.readSubscription(5000)) {
+  while ((subscription = mqtt.readSubscription(5000))) {
     if (subscription == &onoffbutton) {
       Serial.print(F("Got: "));
       Serial.println((char *)onoffbutton.lastread);