diff --git a/libbitdht/src/udp/udplayer.cc b/libbitdht/src/udp/udplayer.cc
index 66e4e0691..4a50e05cb 100644
--- a/libbitdht/src/udp/udplayer.cc
+++ b/libbitdht/src/udp/udplayer.cc
@@ -310,7 +310,7 @@ void UdpLayer::recv_loop()
 }
 
 
-int UdpLayer::sendPkt(const void *data, int size, sockaddr_in &to, int ttl)
+int UdpLayer::sendPkt(const void *data, int size, const sockaddr_in &to, int ttl)
 {
 	/* if ttl is different -> set it */
 	if (ttl != getTTL())
@@ -492,7 +492,7 @@ int UdpLayer::receiveUdpPacket(void *data, int *size, struct sockaddr_in &from)
 	return -1;
 }
 
-int UdpLayer::sendUdpPacket(const void *data, int size, struct sockaddr_in &to)
+int UdpLayer::sendUdpPacket(const void *data, int size, const struct sockaddr_in &to)
 {
 	/* send out */
 #ifdef DEBUG_UDP_LAYER
diff --git a/libbitdht/src/udp/udplayer.h b/libbitdht/src/udp/udplayer.h
index 21fcc5cf1..b82513d43 100644
--- a/libbitdht/src/udp/udplayer.h
+++ b/libbitdht/src/udp/udplayer.h
@@ -60,7 +60,7 @@ class UdpPublisher
 {
 	public:
 virtual ~UdpPublisher() {}
-virtual	int sendPkt(const void *data, int size, struct sockaddr_in &to, int ttl) = 0;
+virtual	int sendPkt(const void *data, int size, const struct sockaddr_in &to, int ttl) = 0;
 };
 
 
@@ -86,7 +86,7 @@ void	recv_loop(); /* uses callback to UdpReceiver */
 
 	/* Higher Level Interface */
 	//int  readPkt(void *data, int *size, struct sockaddr_in &from);
-	int  sendPkt(const void *data, int size, struct sockaddr_in &to, int ttl);
+	int  sendPkt(const void *data, int size, const struct sockaddr_in &to, int ttl);
 
 	/* monitoring / updates */
 	int okay();
@@ -98,7 +98,7 @@ void	recv_loop(); /* uses callback to UdpReceiver */
 	protected:
 
 virtual	int receiveUdpPacket(void *data, int *size, struct sockaddr_in &from);
-virtual	int sendUdpPacket(const void *data, int size, struct sockaddr_in &to);
+virtual	int sendUdpPacket(const void *data, int size, const struct sockaddr_in &to);
  
 	int setTTL(int t);
 	int getTTL();
diff --git a/libbitdht/src/udp/udpstack.cc b/libbitdht/src/udp/udpstack.cc
index 2dc5b1675..b3ca88e75 100644
--- a/libbitdht/src/udp/udpstack.cc
+++ b/libbitdht/src/udp/udpstack.cc
@@ -112,7 +112,7 @@ int UdpStack::recvPkt(void *data, int size, struct sockaddr_in &from)
 	return 1;
 }
 
-int  UdpStack::sendPkt(const void *data, int size, struct sockaddr_in &to, int ttl)
+int  UdpStack::sendPkt(const void *data, int size, const struct sockaddr_in &to, int ttl)
 {
 	/* print packet information */
 #ifdef DEBUG_UDP_RECV
@@ -226,7 +226,7 @@ UdpSubReceiver::UdpSubReceiver(UdpPublisher *pub)
 	return; 
 }
 
-int  UdpSubReceiver::sendPkt(const void *data, int size, struct sockaddr_in &to, int ttl)
+int  UdpSubReceiver::sendPkt(const void *data, int size, const struct sockaddr_in &to, int ttl)
 {
 	/* print packet information */
 #ifdef DEBUG_UDP_RECV
diff --git a/libbitdht/src/udp/udpstack.h b/libbitdht/src/udp/udpstack.h
index 7ce5d26b5..9aeeed3a1 100644
--- a/libbitdht/src/udp/udpstack.h
+++ b/libbitdht/src/udp/udpstack.h
@@ -55,7 +55,7 @@ class UdpSubReceiver: public UdpReceiver
 	UdpSubReceiver(UdpPublisher *pub);
 
 		/* calls mPublisher->sendPkt */
-virtual int sendPkt(const void *data, int size, struct sockaddr_in &to, int ttl);
+virtual int sendPkt(const void *data, int size, const struct sockaddr_in &to, int ttl);
 		/* callback for recved data (overloaded from UdpReceiver) */
 //virtual int recvPkt(void *data, int size, struct sockaddr_in &from) = 0;
 
@@ -87,7 +87,7 @@ int 	removeReceiver(UdpReceiver *recv);
 
 	/* Packet IO */
 		/* pass-through send packets */
-virtual int sendPkt(const void *data, int size, struct sockaddr_in &to, int ttl);
+virtual int sendPkt(const void *data, int size, const struct sockaddr_in &to, int ttl);
 		/* callback for recved data (overloaded from UdpReceiver) */
 
 virtual int recvPkt(void *data, int size, struct sockaddr_in &from);