diff --git a/socks.c b/socks.c
index 1848f081..82872743 100644
--- a/socks.c
+++ b/socks.c
@@ -121,7 +121,7 @@ socks_username_password_auth (struct socks_proxy_info *p,
                "Authentication not possible.");
           return false;
   }
-  snprintf (to_send, sizeof (to_send), "\x01%c%s%c%s", (int) strlen(creds.username),
+  openvpn_snprintf (to_send, sizeof (to_send), "\x01%c%s%c%s", (int) strlen(creds.username),
             creds.username, (int) strlen(creds.password), creds.password);
   size = send (sd, to_send, strlen(to_send), MSG_NOSIGNAL);