diff --git a/libraries/MySensors/MyGateway.cpp b/libraries/MySensors/MyGateway.cpp
index 9040bbc..f9ce0e9 100644
--- a/libraries/MySensors/MyGateway.cpp
+++ b/libraries/MySensors/MyGateway.cpp
@@ -160,7 +160,8 @@ void MyGateway::parseAndSend(char *commandBuffer) {
 	msg.sensor = sensor;
 	msg.type = type;
 	mSetCommand(msg,command);
-	mSetAck(msg,ack==0?false:true);
+	mSetRequestAck(msg,ack==0?false:true);
+	mSetAck(msg,false);
 	msg.set(value);
     ok = sendRoute(msg);
     if (!ok) {
diff --git a/libraries/MySensors/MyMessage.cpp b/libraries/MySensors/MyMessage.cpp
index 96ae96e..ed394b6 100644
--- a/libraries/MySensors/MyMessage.cpp
+++ b/libraries/MySensors/MyMessage.cpp
@@ -14,6 +14,11 @@ MyMessage::MyMessage(uint8_t _sensor, uint8_t _type) {
 }
 
 
+bool MyMessage::isAck() const {
+	return miGetAck();
+}
+
+
 /* Getters for payload converted to desired form */
 void* MyMessage::getCustom() const {
 	return (void *)data;
diff --git a/libraries/MySensors/MyMessage.h b/libraries/MySensors/MyMessage.h
index c3ae7e3..2c5dc21 100644
--- a/libraries/MySensors/MyMessage.h
+++ b/libraries/MySensors/MyMessage.h
@@ -74,28 +74,40 @@ typedef enum {
 // Insert a new bitfield value x into y.
 #define BF_SET(y, x, start, len)    ( y= ((y) &~ BF_MASK(start, len)) | BF_PREP(x, start, len) )
 
-// Getters/setters for special fields in header
+// Getters/setters for special bit fields in header
 #define mSetVersion(_msg,_version) BF_SET(_msg.version_length, _version, 0, 3)
-#define mSetLength(_msg,_length) BF_SET(_msg.version_length, _length, 3, 5)
-
-#define mSetCommand(_msg,_command) BF_SET(_msg.command_ack_payload, _command, 0, 3)
-#define mSetAck(_msg,_command) BF_SET(_msg.command_ack_payload, _command, 3, 1)
-#define mSetPayloadType(_msg, _pt) BF_SET(_msg.command_ack_payload, _pt, 4, 4)
-
 #define mGetVersion(_msg) BF_GET(_msg.version_length, 0, 3)
+
+#define mSetLength(_msg,_length) BF_SET(_msg.version_length, _length, 3, 5)
 #define mGetLength(_msg) BF_GET(_msg.version_length, 3, 5)
 
+#define mSetCommand(_msg,_command) BF_SET(_msg.command_ack_payload, _command, 0, 3)
 #define mGetCommand(_msg) BF_GET(_msg.command_ack_payload, 0, 3)
-#define mGetAck(_msg) BF_GET(_msg.command_ack_payload, 3, 1)
-#define mGetPayloadType(_msg) BF_GET(_msg.command_ack_payload, 4, 4)
+
+#define mSetRequestAck(_msg,_rack) BF_SET(_msg.command_ack_payload, _rack, 3, 1)
+#define mGetRequestAck(_msg) BF_GET(_msg.command_ack_payload, 3, 1)
+
+#define mSetAck(_msg,_ack) BF_SET(_msg.command_ack_payload, _ack, 4, 1)
+#define mGetAck(_msg) BF_GET(_msg.command_ack_payload, 4, 1)
+
+#define mSetPayloadType(_msg, _pt) BF_SET(_msg.command_ack_payload, _pt, 5, 3)
+#define mGetPayloadType(_msg) BF_GET(_msg.command_ack_payload, 5, 3)
 
 
 // internal access for special fields
+#define miSetPayloadType(_pt) BF_SET(command_ack_payload, _pt, 4, 4)
 #define miGetPayloadType() BF_GET(command_ack_payload, 4, 4)
-#define miGetLength() BF_GET(version_length, 3, 5)
 
 #define miSetLength(_length) BF_SET(version_length, _length, 3, 5)
-#define miSetPayloadType(_pt) BF_SET(command_ack_payload, _pt, 4, 4)
+#define miGetLength() BF_GET(version_length, 3, 5)
+
+#define miSetRequestAck(_rack) BF_SET(command_ack_payload, _rack, 3, 1)
+#define miGetRequestAck() BF_GET(command_ack_payload, 3, 1)
+
+#define miSetAck(_ack) BF_SET(command_ack_payload, _ack, 4, 1)
+#define miGetAck() BF_GET(command_ack_payload, 4, 1)
+
+
 
 
 class MyMessage
@@ -122,6 +134,9 @@ public:
 	int getInt() const;
 	unsigned int getUInt() const;
 
+	// Getter for ack-flag. True if this is an ack message.
+	bool isAck() const;
+
 	// Setters for building message "on the fly"
 	MyMessage& setType(uint8_t type);
 	MyMessage& setSensor(uint8_t sensor);
@@ -141,8 +156,9 @@ public:
 	uint8_t version_length;      // 3 bit - Protocol version
 			                     // 5 bit - Length of payload
 	uint8_t command_ack_payload; // 3 bit - Command type
-	                             // 1 bit - Indicator that receiver should send an ack back.
-	                             // 4 bit - Payload data type
+	                             // 1 bit - Request an ack - Indicator that receiver should send an ack back.
+								 // 1 bit - Is ack messsage - Indicator that this is the actual ack message.
+	                             // 3 bit - Payload data type
 	uint8_t sender;          	 // 8 bit - Id of sender node
 	uint8_t last;            	 // 8 bit - Id of last node this message passed
 	uint8_t destination;     	 // 8 bit - Id of destination node
diff --git a/libraries/MySensors/MySensor.cpp b/libraries/MySensors/MySensor.cpp
index a0ddcf2..ad342b2 100644
--- a/libraries/MySensors/MySensor.cpp
+++ b/libraries/MySensors/MySensor.cpp
@@ -22,7 +22,8 @@ inline MyMessage& build (MyMessage &msg, uint8_t sender, uint8_t destination, ui
 	msg.sensor = sensor;
 	msg.type = type;
 	mSetCommand(msg,command);
-	mSetAck(msg,enableAck);
+	mSetRequestAck(msg,enableAck);
+	mSetAck(msg,false);
 	return msg;
 }
 
@@ -226,7 +227,7 @@ boolean MySensor::sendWrite(uint8_t next, MyMessage &message, bool broadcast) {
 bool MySensor::send(MyMessage &message, bool enableAck) {
 	message.sender = nc.nodeId;
 	mSetCommand(message,C_SET);
-    mSetAck(message,enableAck);
+    mSetRequestAck(message,enableAck);
 	return sendRoute(message);
 }
 
@@ -293,10 +294,11 @@ boolean MySensor::process() {
 		return false;
 	} else if (destination == nc.nodeId) {
 		// Check if sender requests an ack back.
-		if (mGetAck(msg)) {
+		if (mGetRequestAck(msg)) {
 			// Copy message
 			ack = msg;
-			mSetAck(ack,false); // Reply without ack flag (otherwise we would end up in an eternal loop)
+			mSetRequestAck(ack,false); // Reply without ack flag (otherwise we would end up in an eternal loop)
+			mSetAck(ack,true);
 			ack.sender = nc.nodeId;
 			ack.destination = msg.sender;
 			sendRoute(ack);