diff --git a/README.md b/README.md
index 83176919..c3b5cce4 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,8 @@ Full API documentation is available here: http://pubsubclient.knolleary.net
 
  - It can only publish QoS 0 messages. It can subscribe at QoS 0 or QoS 1.
  - The maximum message size, including header, is **128 bytes** by default. This
-   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h`.
+   is configurable via `MQTT_MAX_PACKET_SIZE` in `PubSubClient.h` or at runtime
+   using PubSubClient::setBufferSize().
  - The keepalive interval is set to 15 seconds by default. This is configurable
    via `MQTT_KEEPALIVE` in `PubSubClient.h`.
  - The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by
diff --git a/examples/mqtt_auth/mqtt_auth.ino b/examples/mqtt_auth/mqtt_auth.ino
index e9f7b180..04bd7bb2 100755
--- a/examples/mqtt_auth/mqtt_auth.ino
+++ b/examples/mqtt_auth/mqtt_auth.ino
@@ -27,9 +27,9 @@ void setup()
 {
   Ethernet.begin(mac, ip);
   // Note - the default maximum packet size is 128 bytes. If the
-  // combined length of clientId, username and password exceed this,
-  // you will need to increase the value of MQTT_MAX_PACKET_SIZE in
-  // PubSubClient.h
+  // combined length of clientId, username and password exceed this use the
+  // following to increase the buffer size:
+  // client.setBufferSize(255);
   
   if (client.connect("arduinoClient", "testuser", "testpass")) {
     client.publish("outTopic","hello world");
diff --git a/src/PubSubClient.cpp b/src/PubSubClient.cpp
index 5932bdbe..73714bd2 100755
--- a/src/PubSubClient.cpp
+++ b/src/PubSubClient.cpp
@@ -12,12 +12,16 @@ PubSubClient::PubSubClient() {
     this->_client = NULL;
     this->stream = NULL;
     setCallback(NULL);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(Client& client) {
     this->_state = MQTT_DISCONNECTED;
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, Client& client) {
@@ -25,12 +29,16 @@ PubSubClient::PubSubClient(IPAddress addr, uint16_t port, Client& client) {
     setServer(addr, port);
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
     setServer(addr,port);
     setClient(client);
     setStream(stream);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client) {
     this->_state = MQTT_DISCONNECTED;
@@ -38,6 +46,8 @@ PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATUR
     setCallback(callback);
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
@@ -45,6 +55,8 @@ PubSubClient::PubSubClient(IPAddress addr, uint16_t port, MQTT_CALLBACK_SIGNATUR
     setCallback(callback);
     setClient(client);
     setStream(stream);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, Client& client) {
@@ -52,12 +64,16 @@ PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, Client& client) {
     setServer(ip, port);
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
     setServer(ip,port);
     setClient(client);
     setStream(stream);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client) {
     this->_state = MQTT_DISCONNECTED;
@@ -65,6 +81,8 @@ PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE,
     setCallback(callback);
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
@@ -72,6 +90,8 @@ PubSubClient::PubSubClient(uint8_t *ip, uint16_t port, MQTT_CALLBACK_SIGNATURE,
     setCallback(callback);
     setClient(client);
     setStream(stream);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 
 PubSubClient::PubSubClient(const char* domain, uint16_t port, Client& client) {
@@ -79,12 +99,16 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, Client& client) {
     setServer(domain,port);
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(const char* domain, uint16_t port, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
     setServer(domain,port);
     setClient(client);
     setStream(stream);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client) {
     this->_state = MQTT_DISCONNECTED;
@@ -92,6 +116,8 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGN
     setCallback(callback);
     setClient(client);
     this->stream = NULL;
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
 }
 PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGNATURE, Client& client, Stream& stream) {
     this->_state = MQTT_DISCONNECTED;
@@ -99,6 +125,12 @@ PubSubClient::PubSubClient(const char* domain, uint16_t port, MQTT_CALLBACK_SIGN
     setCallback(callback);
     setClient(client);
     setStream(stream);
+    this->buffer_size = MQTT_MAX_PACKET_SIZE;
+    this->buffer = (uint8_t*)malloc(MQTT_MAX_PACKET_SIZE);
+}
+
+PubSubClient::~PubSubClient() {
+  free(this->buffer);
 }
 
 boolean PubSubClient::connect(const char *id) {
@@ -266,13 +298,13 @@ uint16_t PubSubClient::readPacket(uint8_t* lengthLength) {
                 this->stream->write(digit);
             }
         }
-        if (len < MQTT_MAX_PACKET_SIZE) {
+        if (len < this->buffer_size) {
             buffer[len] = digit;
         }
         len++;
     }
 
-    if (!this->stream && len > MQTT_MAX_PACKET_SIZE) {
+    if (!this->stream && len > this->buffer_size) {
         len = 0; // This will cause the packet to be ignored.
     }
 
@@ -356,7 +388,7 @@ boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigne
 
 boolean PubSubClient::publish(const char* topic, const uint8_t* payload, unsigned int plength, boolean retained) {
     if (connected()) {
-        if (MQTT_MAX_PACKET_SIZE < 5 + 2+strlen(topic) + plength) {
+        if (this->buffer_size < 5 + 2+strlen(topic) + plength) {
             // Too long
             return false;
         }
@@ -471,7 +503,7 @@ boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
     if (qos < 0 || qos > 1) {
         return false;
     }
-    if (MQTT_MAX_PACKET_SIZE < 9 + strlen(topic)) {
+    if (this->buffer_size < 9 + strlen(topic)) {
         // Too long
         return false;
     }
@@ -492,7 +524,7 @@ boolean PubSubClient::subscribe(const char* topic, uint8_t qos) {
 }
 
 boolean PubSubClient::unsubscribe(const char* topic) {
-    if (MQTT_MAX_PACKET_SIZE < 9 + strlen(topic)) {
+    if (this->buffer_size < 9 + strlen(topic)) {
         // Too long
         return false;
     }
@@ -586,3 +618,13 @@ PubSubClient& PubSubClient::setStream(Stream& stream){
 int PubSubClient::state() {
     return this->_state;
 }
+
+boolean PubSubClient::setBufferSize(uint16_t size) {
+  this->buffer = (uint8_t*)realloc(this->buffer, size);
+  this->buffer_size = size;
+  return (this->buffer == NULL);
+}
+
+uint16_t PubSubClient::getBufferSize() {
+  return this->buffer_size;
+}
diff --git a/src/PubSubClient.h b/src/PubSubClient.h
index be4bd674..c8b0ff14 100755
--- a/src/PubSubClient.h
+++ b/src/PubSubClient.h
@@ -21,7 +21,7 @@
 #define MQTT_VERSION MQTT_VERSION_3_1_1
 #endif
 
-// MQTT_MAX_PACKET_SIZE : Maximum packet size
+// MQTT_MAX_PACKET_SIZE : Maximum packet size. Override with setBufferSize().
 #ifndef MQTT_MAX_PACKET_SIZE
 #define MQTT_MAX_PACKET_SIZE 128
 #endif
@@ -83,7 +83,8 @@
 class PubSubClient {
 private:
    Client* _client;
-   uint8_t buffer[MQTT_MAX_PACKET_SIZE];
+   uint8_t* buffer;
+   uint16_t buffer_size;
    uint16_t nextMsgId;
    unsigned long lastOutActivity;
    unsigned long lastInActivity;
@@ -115,6 +116,8 @@ class PubSubClient {
    PubSubClient(const char*, uint16_t, MQTT_CALLBACK_SIGNATURE,Client& client);
    PubSubClient(const char*, uint16_t, MQTT_CALLBACK_SIGNATURE,Client& client, Stream&);
 
+   ~PubSubClient();
+
    PubSubClient& setServer(IPAddress ip, uint16_t port);
    PubSubClient& setServer(uint8_t * ip, uint16_t port);
    PubSubClient& setServer(const char * domain, uint16_t port);
@@ -138,6 +141,8 @@ class PubSubClient {
    boolean loop();
    boolean connected();
    int state();
+   boolean setBufferSize(uint16_t size);
+   uint16_t getBufferSize();
 };
 
 
diff --git a/tests/src/receive_spec.cpp b/tests/src/receive_spec.cpp
index 54a62ee5..29975190 100644
--- a/tests/src/receive_spec.cpp
+++ b/tests/src/receive_spec.cpp
@@ -160,6 +160,43 @@ int test_receive_oversized_message() {
     END_IT
 }
 
+int test_resize_buffer() {
+    IT("receives a message larger than the default maximum");
+    reset_callback();
+
+    ShimClient shimClient;
+    shimClient.setAllowConnect(true);
+
+    byte connack[] = { 0x20, 0x02, 0x00, 0x00 };
+    shimClient.respond(connack,4);
+
+    PubSubClient client(server, 1883, callback, shimClient);
+    int rc = client.connect((char*)"client_test1");
+    IS_TRUE(rc);
+
+    int length = MQTT_MAX_PACKET_SIZE+1;
+    client.setBufferSize(length);
+    byte publish[] = {0x30,length-2,0x0,0x5,0x74,0x6f,0x70,0x69,0x63,0x70,0x61,0x79,0x6c,0x6f,0x61,0x64};
+    byte bigPublish[length];
+    memset(bigPublish,'A',length);
+    bigPublish[length] = 'B';
+    memcpy(bigPublish,publish,16);
+    shimClient.respond(bigPublish,length);
+
+    rc = client.loop();
+
+    IS_TRUE(rc);
+
+    IS_TRUE(callback_called);
+    IS_TRUE(strcmp(lastTopic,"topic")==0);
+    IS_TRUE(lastLength == length-9);
+    IS_TRUE(memcmp(lastPayload,bigPublish+9,lastLength)==0);
+
+    IS_FALSE(shimClient.error());
+
+    END_IT
+}
+
 int test_receive_oversized_stream_message() {
     IT("drops an oversized message");
     reset_callback();
@@ -242,6 +279,7 @@ int main()
     test_receive_stream();
     test_receive_max_sized_message();
     test_receive_oversized_message();
+    test_resize_buffer();
     test_receive_oversized_stream_message();
     test_receive_qos1();