diff --git a/src/mqttsn-messages.cpp b/src/mqttsn-messages.cpp
index 91326a5..d61bc88 100644
--- a/src/mqttsn-messages.cpp
+++ b/src/mqttsn-messages.cpp
@@ -180,12 +180,13 @@ void MQTTSN::dispatch() {
     }
 
     waiting_for_response = false;
+    memset(response_message, 0, MAX_BUFFER_SIZE);
 }
 
 void MQTTSN::send_message() {
     message_header* hdr = reinterpret_cast<message_header*>(message_buffer);
 
-#ifdef USE_RF12
+    #ifdef USE_RF12
     while (!rf12_canSend()) {
         rf12_recvDone();
         Sleepy::loseSomeTime(32);
diff --git a/src/mqttsn.h b/src/mqttsn.h
index 746c7ce..fd59fdb 100644
--- a/src/mqttsn.h
+++ b/src/mqttsn.h
@@ -98,70 +98,70 @@ struct message_header {
     uint8_t type;
 };
 
-struct msg_advertise : public message_header {
+struct __attribute__ ((packed)) msg_advertise : public message_header {
     uint8_t gw_id;
     uint16_t duration;
 };
 
-struct msg_searchgw : public message_header {
+struct __attribute__ ((packed)) msg_searchgw : public message_header {
     uint8_t radius;
 };
 
-struct msg_gwinfo : public message_header {
+struct __attribute__ ((packed)) msg_gwinfo : public message_header {
     uint8_t gw_id;
     char gw_add[0];
 };
 
-struct msg_connect : public message_header {
+struct __attribute__ ((packed)) msg_connect : public message_header {
     uint8_t flags;
     uint8_t protocol_id;
     uint16_t duration;
     char client_id[0];
 };
 
-struct msg_connack : public message_header {
+struct __attribute__ ((packed)) msg_connack : public message_header {
     return_code_t return_code;
 };
 
-struct msg_willtopic : public message_header {
+struct __attribute__ ((packed)) msg_willtopic : public message_header {
     uint8_t flags;
     char will_topic[0];
 };
 
-struct msg_willmsg : public message_header {
+struct __attribute__ ((packed)) msg_willmsg : public message_header {
     char willmsg[0];
 };
 
-struct msg_register : public message_header {
+struct __attribute__ ((packed)) msg_register : public message_header {
     uint16_t topic_id;
     uint16_t message_id;
     char topic_name[0];
 };
 
-struct msg_regack : public message_header {
+struct __attribute__ ((packed)) msg_regack : public message_header {
     uint16_t topic_id;
     uint16_t message_id;
     uint8_t return_code;
 };
 
-struct msg_publish : public message_header {
+struct __attribute__ ((packed)) msg_publish : public message_header {
     uint8_t flags;
     uint16_t topic_id;
     uint16_t message_id;
     char data[0];
 };
 
-struct msg_puback : public message_header {
+struct __attribute__ ((packed)) msg_puback : public message_header {
     uint16_t topic_id;
     uint16_t message_id;
     uint8_t return_code;
 };
 
-struct msg_pubqos2 : public message_header {
+struct __attribute__ ((packed)) msg_pubqos2 : public message_header {
     uint16_t message_id;
 };
 
-struct msg_subscribe : public message_header {
+struct __attribute__ ((packed)) msg_subscribe : public message_header {
     uint8_t flags;
     uint16_t message_id;
     union {
@@ -170,14 +170,14 @@ struct msg_subscribe : public message_header {
     };
 };
 
-struct msg_suback : public message_header {
+struct __attribute__ ((packed)) msg_suback : public message_header {
     uint8_t flags;
     uint16_t topic_id;
     uint16_t message_id;
     uint8_t return_code;
 };
 
-struct msg_unsubscribe : public message_header {
+struct __attribute__ ((packed)) msg_unsubscribe : public message_header {
     uint8_t flags;
     uint16_t message_id;
     union {
@@ -186,23 +186,23 @@ struct msg_unsubscribe : public message_header {
     };
 };
 
-struct msg_unsuback : public message_header {
+struct __attribute__ ((packed)) msg_unsuback : public message_header {
     uint16_t message_id;
 };
 
-struct msg_pingreq : public message_header {
+struct __attribute__ ((packed)) msg_pingreq : public message_header {
     char client_id[0];
 };
 
-struct msg_disconnect : public message_header {
+struct __attribute__ ((packed)) msg_disconnect : public message_header {
     uint16_t duration;
 };
 
-struct msg_willtopicresp : public message_header {
+struct __attribute__ ((packed)) msg_willtopicresp : public message_header {
     uint8_t return_code;
 };
 
-struct msg_willmsgresp : public message_header {
+struct __attribute__ ((packed)) msg_willmsgresp : public message_header {
     uint8_t return_code;
 };