diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index ba0e8e6337c0a3..7890b395e629b6 100644
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -322,6 +322,8 @@ tcp_app_win - INTEGER
 	Reserve max(window/2^tcp_app_win, mss) of window for application
 	buffer. Value 0 is special, it means that nothing is reserved.
 
+	Possible values are [0, 31], inclusive.
+
 	Default: 31
 
 tcp_autocorking - BOOLEAN
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 495c58e442e2a1..1f22e72074fdca 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -38,6 +38,7 @@ static int ip_local_port_range_min[] = { 1, 1 };
 static int ip_local_port_range_max[] = { 65535, 65535 };
 static int tcp_adv_win_scale_min = -31;
 static int tcp_adv_win_scale_max = 31;
+static int tcp_app_win_max = 31;
 static int tcp_min_snd_mss_min = TCP_MIN_SND_MSS;
 static int tcp_min_snd_mss_max = 65535;
 static int ip_privileged_port_min;
@@ -1168,6 +1169,8 @@ static struct ctl_table ipv4_net_table[] = {
 		.maxlen		= sizeof(u8),
 		.mode		= 0644,
 		.proc_handler	= proc_dou8vec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= &tcp_app_win_max,
 	},
 	{
 		.procname	= "tcp_adv_win_scale",