diff --git a/include/net/tcp.h b/include/net/tcp.h
index 9e68e25..18c246c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -464,7 +464,7 @@
 				     __u16 *mss);
 
 extern __u32 cookie_init_timestamp(struct request_sock *req);
-extern void cookie_check_timestamp(struct tcp_options_received *tcp_opt);
+extern bool cookie_check_timestamp(struct tcp_options_received *tcp_opt);
 
 /* From net/ipv6/syncookies.c */
 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);