diff --git a/src/MqttClient.cpp b/src/MqttClient.cpp
index 221b230..f832d60 100644
--- a/src/MqttClient.cpp
+++ b/src/MqttClient.cpp
@@ -171,9 +171,9 @@ int MqttClient::messageRetain() const
   return -1;
 }
 
-int MqttClient::beginMessage(const char* topic, unsigned long size, bool retain, uint8_t qos, bool dup)
+int MqttClient::beginMessage(const String& topic, unsigned long size, bool retain, uint8_t qos, bool dup)
 {
-  _txMessageTopic = topic;
+  _txMessageTopic = topic.c_str();
   _txMessageRetain = retain;
   _txMessageQoS = qos;
   _txMessageDup = dup;
@@ -191,19 +191,9 @@ int MqttClient::beginMessage(const char* topic, unsigned long size, bool retain,
   return 1;
 }
 
-int MqttClient::beginMessage(const String& topic, unsigned long size, bool retain, uint8_t qos, bool dup)
-{
-  return beginMessage(topic.c_str(), size, retain, qos, dup);
-}
-
-int MqttClient::beginMessage(const char* topic, bool retain, uint8_t qos, bool dup)
-{
-  return beginMessage(topic, 0xffffffffL, retain, qos, dup);
-}
-
 int MqttClient::beginMessage(const String& topic, bool retain, uint8_t qos, bool dup)
 {
-  return beginMessage(topic.c_str(), retain, qos, dup);
+  return beginMessage(topic, 0xffffffffL, retain, qos, dup);
 }
 
 int MqttClient::endMessage()
@@ -259,9 +249,9 @@ int MqttClient::endMessage()
   return 1;
 }
 
-int MqttClient::beginWill(const char* topic, unsigned short size, bool retain, uint8_t qos)
+int MqttClient::beginWill(const String& topic, unsigned short size, bool retain, uint8_t qos)
 {
-  int topicLength = strlen(topic);
+  int topicLength = topic.length();
   size_t willLength = (2 + topicLength + 2 + size);
 
   if (qos > 2) {
@@ -272,7 +262,7 @@ int MqttClient::beginWill(const char* topic, unsigned short size, bool retain, u
 
   _txBuffer = _willBuffer;
   _txBufferIndex = 0;
-  writeString(topic, topicLength);
+  writeString(topic.c_str(), topic.length());
   write16(0); // dummy size for now
   _willMessageIndex = _txBufferIndex;
 
@@ -284,19 +274,9 @@ int MqttClient::beginWill(const char* topic, unsigned short size, bool retain, u
   return 0;
 }
 
-int MqttClient::beginWill(const String& topic, unsigned short size, bool retain, uint8_t qos)
-{
-  return beginWill(topic.c_str(), size, retain, qos);
-}
-
-int MqttClient::beginWill(const char* topic, bool retain, uint8_t qos)
-{
-  return beginWill(topic, _tx_payload_buffer_size, retain, qos);
-}
-
 int MqttClient::beginWill(const String& topic, bool retain, uint8_t qos)
 {
-  return beginWill(topic.c_str(), retain, qos);
+  return beginWill(topic, _tx_payload_buffer_size, retain, qos);
 }
 
 int MqttClient::endWill()
@@ -314,9 +294,10 @@ int MqttClient::endWill()
   return 1;
 }
 
-int MqttClient::subscribe(const char* topic, uint8_t qos)
+int MqttClient::subscribe(const String& topic, uint8_t qos)
+
 {
-  int topicLength = strlen(topic);
+  int topicLength = topic.length();
   int remainingLength = topicLength + 5;
 
   if (qos > 2) {
@@ -334,7 +315,7 @@ int MqttClient::subscribe(const char* topic, uint8_t qos)
 
   beginPacket(MQTT_SUBSCRIBE, 0x02, remainingLength, packetBuffer);
   write16(_txPacketId);
-  writeString(topic, topicLength);
+  writeString(topic.c_str(), topicLength);
   write8(qos);
 
   if (!endPacket()) {
@@ -362,14 +343,9 @@ int MqttClient::subscribe(const char* topic, uint8_t qos)
   return 0;
 }
 
-int MqttClient::subscribe(const String& topic, uint8_t qos)
-{
-  return subscribe(topic.c_str(), qos);
-}
-
-int MqttClient::unsubscribe(const char* topic)
+int MqttClient::unsubscribe(const String& topic)
 {
-  int topicLength = strlen(topic);
+  int topicLength = topic.length();
   int remainingLength = topicLength + 4;
 
   _txPacketId++;
@@ -382,7 +358,7 @@ int MqttClient::unsubscribe(const char* topic)
 
   beginPacket(MQTT_UNSUBSCRIBE, 0x02, remainingLength, packetBuffer);
   write16(_txPacketId);
-  writeString(topic, topicLength);
+  writeString(topic.c_str(), topicLength);
 
   if (!endPacket()) {
     stop();
@@ -406,11 +382,6 @@ int MqttClient::unsubscribe(const char* topic)
   return 0;
 }
 
-int MqttClient::unsubscribe(const String& topic)
-{
-  return unsubscribe(topic.c_str());
-}
-
 void MqttClient::poll()
 {
   if (clientAvailable() == 0 && !clientConnected()) {
@@ -448,9 +419,9 @@ void MqttClient::poll()
         if ((b & 0x80) == 0) { // length done
           bool malformedResponse = false;
 
-          if (_rxType == MQTT_CONNACK || 
+          if (_rxType == MQTT_CONNACK ||
               _rxType == MQTT_PUBACK  ||
-              _rxType == MQTT_PUBREC  || 
+              _rxType == MQTT_PUBREC  ||
               _rxType == MQTT_PUBCOMP ||
               _rxType == MQTT_UNSUBACK) {
             malformedResponse = (_rxFlags != 0x00 || _rxLength != 2);
@@ -458,7 +429,7 @@ void MqttClient::poll()
             malformedResponse = ((_rxFlags & 0x06) == 0x06);
           } else if (_rxType == MQTT_PUBREL) {
             malformedResponse = (_rxFlags != 0x02 || _rxLength != 2);
-          } else if (_rxType == MQTT_SUBACK) { 
+          } else if (_rxType == MQTT_SUBACK) {
             malformedResponse = (_rxFlags != 0x00 || _rxLength != 3);
           } else if (_rxType == MQTT_PINGRESP) {
             malformedResponse = (_rxFlags != 0x00 || _rxLength != 0);
@@ -531,7 +502,7 @@ void MqttClient::poll()
         if (_rxMessageIndex == 2) {
           _rxMessageTopicLength = (_rxMessageBuffer[0] << 8) | _rxMessageBuffer[1];
           _rxLength -= 2;
-          
+
           _rxMessageTopic = "";
           _rxMessageTopic.reserve(_rxMessageTopicLength);
 
@@ -722,7 +693,7 @@ int MqttClient::read(uint8_t *buf, size_t size)
 
       if (b == -1) {
         break;
-      } 
+      }
 
       result++;
       *buf++ = b;
@@ -775,22 +746,11 @@ MqttClient::operator bool()
   return true;
 }
 
-void MqttClient::setId(const char* id)
-{
-  _id = id;
-}
-
 void MqttClient::setId(const String& id)
 {
   _id = id;
 }
 
-void MqttClient::setUsernamePassword(const char* username, const char* password)
-{
-  _username = username;
-  _password = password;
-}
-
 void MqttClient::setUsernamePassword(const String& username, const String& password)
 {
   _username = username;
@@ -819,7 +779,7 @@ void MqttClient::setTxPayloadSize(unsigned short size)
     _txPayloadBuffer = NULL;
     _txPayloadBufferIndex = 0;
   }
-    
+
   _tx_payload_buffer_size = size;
 }
 
diff --git a/src/MqttClient.h b/src/MqttClient.h
index 522f023..5b457a9 100644
--- a/src/MqttClient.h
+++ b/src/MqttClient.h
@@ -59,21 +59,15 @@ class MqttClient : public Client {
   int messageQoS() const;
   int messageRetain() const;
 
-  int beginMessage(const char* topic, unsigned long size, bool retain = false, uint8_t qos = 0, bool dup = false);
   int beginMessage(const String& topic, unsigned long size, bool retain = false, uint8_t qos = 0, bool dup = false);
-  int beginMessage(const char* topic, bool retain = false, uint8_t qos = 0, bool dup = false);
   int beginMessage(const String& topic, bool retain = false, uint8_t qos = 0, bool dup = false);
   int endMessage();
 
-  int beginWill(const char* topic, unsigned short size, bool retain, uint8_t qos);
   int beginWill(const String& topic, unsigned short size, bool retain, uint8_t qos);
-  int beginWill(const char* topic, bool retain, uint8_t qos);
   int beginWill(const String& topic, bool retain, uint8_t qos);
   int endWill();
 
-  int subscribe(const char* topic, uint8_t qos = 0);
   int subscribe(const String& topic, uint8_t qos = 0);
-  int unsubscribe(const char* topic);
   int unsubscribe(const String& topic);
 
   void poll();
@@ -95,10 +89,8 @@ class MqttClient : public Client {
   virtual uint8_t connected();
   virtual operator bool();
 
-  void setId(const char* id);
   void setId(const String& id);
 
-  void setUsernamePassword(const char* username, const char* password);
   void setUsernamePassword(const String& username, const String& password);
 
   void setCleanSession(bool cleanSession);