Installing server

[nikillpop]

Hello i installed the chat server and client, i also made the client but when i tried to make the server it gave me this error can you fix this please "src/server.c: In function ‘main’:
src/server.c:94:33: error: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘size_t {aka unsigned int}’ [-Werror=format=]
sprintf(client->name, "guest%lu", uid);
^
"