diff --git a/include/net/tcp.h b/include/net/tcp.h
index 914a60c7ad62..4fee0424af7e 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -346,8 +346,6 @@ static inline void tcp_dec_quickack_mode(struct sock *sk,
 	}
 }
 
-extern void tcp_enter_quickack_mode(struct sock *sk);
-
 #define	TCP_ECN_OK		1
 #define	TCP_ECN_QUEUE_CWR	2
 #define	TCP_ECN_DEMAND_CWR	4
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fabc09a58d7f..eaf20e7e61da 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -182,7 +182,7 @@ static void tcp_incr_quickack(struct sock *sk)
 		icsk->icsk_ack.quick = min(quickacks, TCP_MAX_QUICKACKS);
 }
 
-void tcp_enter_quickack_mode(struct sock *sk)
+static void tcp_enter_quickack_mode(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	tcp_incr_quickack(sk);