diff --git a/src/network/network_internal.h b/src/network/network_internal.h
--- a/src/network/network_internal.h
+++ b/src/network/network_internal.h
@@ -119,7 +119,7 @@ void NetworkFreeLocalCommandQueue();
 void NetworkSyncCommandQueue(NetworkClientSocket *cs);
 
 void ShowNetworkError(StringID error_string);
-void NetworkTextMessage(NetworkAction action, TextColour colour, bool self_send, const std::string &name, const std::string &str = "", int64 data = 0);
+void NetworkTextMessage(NetworkAction action, TextColour colour, bool self_send, const std::string &name, const std::string &str = "", int64 data = 0, const std::string &data_str = "");
 uint NetworkCalculateLag(const NetworkClientSocket *cs);
 StringID GetNetworkErrorMsg(NetworkErrorCode err);
 bool NetworkMakeClientNameUnique(std::string &new_name);