extern blob tcp_fastopen_nodata; /* for zero-data TFO connect requests */
extern BOOL tcp_nodelay; /* Controls TCP_NODELAY on daemon */
-extern int tcp_out_fastopen; /* 0: no 1: conn used 2: useful */
+extern tfo_state_t tcp_out_fastopen; /* 0: no 1: conn used 2: useful */
#ifdef USE_TCP_WRAPPERS
extern uschar *tcp_wrappers_daemon_name; /* tcpwrappers daemon lookup name */
#endif