diff --git a/src/network/network_udp.cpp b/src/network/network_udp.cpp
--- a/src/network/network_udp.cpp
+++ b/src/network/network_udp.cpp
@@ -244,7 +244,7 @@ void ServerNetworkUDPSocketHandler::Rece
 	uint8 in_reply_count = 0;
 	size_t packet_len = 0;
 
-	DEBUG(net, 6, "[udp] newgrf data request from %s", client_addr->GetAddressAsString());
+	DEBUG(net, 6, "[udp] newgrf data request from %s", client_addr->GetAddressAsString().c_str());
 
 	num_grfs = p->Recv_uint8 ();
 	if (num_grfs > NETWORK_MAX_GRF_COUNT) return;
@@ -307,7 +307,7 @@ void ClientNetworkUDPSocketHandler::Rece
 	/* Just a fail-safe.. should never happen */
 	if (_network_udp_server) return;
 
-	DEBUG(net, 4, "[udp] server response from %s", client_addr->GetAddressAsString());
+	DEBUG(net, 4, "[udp] server response from %s", client_addr->GetAddressAsString().c_str());
 
 	/* Find next item */
 	item = NetworkGameListAddItem(*client_addr);
@@ -407,7 +407,7 @@ void ClientNetworkUDPSocketHandler::Rece
 	uint8 num_grfs;
 	uint i;
 
-	DEBUG(net, 6, "[udp] newgrf data reply from %s", client_addr->GetAddressAsString());
+	DEBUG(net, 6, "[udp] newgrf data reply from %s", client_addr->GetAddressAsString().c_str());
 
 	num_grfs = p->Recv_uint8 ();
 	if (num_grfs > NETWORK_MAX_GRF_COUNT) return;
@@ -477,7 +477,7 @@ void NetworkUDPQueryMasterServer()
 
 	_udp_client_socket->SendPacket(&p, &out_addr, true);
 
-	DEBUG(net, 2, "[udp] master server queried at %s", out_addr.GetAddressAsString());
+	DEBUG(net, 2, "[udp] master server queried at %s", out_addr.GetAddressAsString().c_str());
 }
 
 /** Find all servers */
@@ -541,8 +541,8 @@ static void NetworkUDPAdvertiseThread()
 	if (_session_key == 0 && session_key_retries++ == 2) {
 		DEBUG(net, 0, "[udp] advertising to the master server is failing");
 		DEBUG(net, 0, "[udp]   we are not receiving the session key from the server");
-		DEBUG(net, 0, "[udp]   please allow udp packets from %s to you to be delivered", out_addr.GetAddressAsString(false));
-		DEBUG(net, 0, "[udp]   please allow udp packets from you to %s to be delivered", out_addr.GetAddressAsString(false));
+		DEBUG(net, 0, "[udp]   please allow udp packets from %s to you to be delivered", out_addr.GetAddressAsString(false).c_str());
+		DEBUG(net, 0, "[udp]   please allow udp packets from you to %s to be delivered", out_addr.GetAddressAsString(false).c_str());
 	}
 	if (_session_key != 0 && _network_advertise_retries == 0) {
 		DEBUG(net, 0, "[udp] advertising to the master server is failing");