diff --git a/src/PubSubClient.cpp b/src/PubSubClient.cpp
index 9658c4a..5932bdb 100755
--- a/src/PubSubClient.cpp
+++ b/src/PubSubClient.cpp
@@ -306,12 +306,10 @@ boolean PubSubClient::loop() {
                 uint8_t type = buffer[0]&0xF0;
                 if (type == MQTTPUBLISH) {
                     if (callback) {
-                        uint16_t tl = (buffer[llen+1]<<8)+buffer[llen+2];
-                        char topic[tl+1];
-                        for (uint16_t i=0;i<tl;i++) {
-                            topic[i] = buffer[llen+3+i];
-                        }
-                        topic[tl] = 0;
+                        uint16_t tl = (buffer[llen+1]<<8)+buffer[llen+2]; /* topic length in bytes */
+                        memmove(buffer+llen+2,buffer+llen+3,tl); /* move topic inside buffer 1 byte to front */
+                        buffer[llen+2+tl] = 0; /* end the topic as a 'C' string with \x00 */
+                        char *topic = (char*) buffer+llen+2;
                         // msgId only present for QOS>0
                         if ((buffer[0]&0x06) == MQTTQOS1) {
                             msgId = (buffer[llen+3+tl]<<8)+buffer[llen+3+tl+1];