diff --git a/src/network/network_server.cpp b/src/network/network_server.cpp
--- a/src/network/network_server.cpp
+++ b/src/network/network_server.cpp
@@ -1776,7 +1776,7 @@ void NetworkServerSendRcon(ClientID clie
 	SEND_COMMAND(PACKET_SERVER_RCON)(NetworkFindClientStateFromClientID(client_id), colour_code, string);
 }
 
-void NetworkServerSendError(ClientID client_id, NetworkErrorCode error)
+static void NetworkServerSendError(ClientID client_id, NetworkErrorCode error)
 {
 	SEND_COMMAND(PACKET_SERVER_ERROR)(NetworkFindClientStateFromClientID(client_id), error);
 }