diff --git a/man7/tcp.7 b/man7/tcp.7
index 34dd7ef2d..7005795af 100644
--- a/man7/tcp.7
+++ b/man7/tcp.7
@@ -236,6 +236,18 @@ default value of 2 implies that the space
 used for the application buffer is one fourth that of the
 total.
 .TP
+.IR tcp_allowed_congestion_control " (String; default: see text; since Linux 2.4.20)"
+.\" The following is from 2.6.28-rc4: Documentation/networking/ip-sysctl.txt
+Show/set the congestion control choices available to non-privileged
+processes (see the description of the
+.B TCP_CONGESTION
+socket option).
+The list is a subset of those listed in
+.IR tcp_available_congestion_control .
+.\" FIXME How are the items in this delimited? Null bytes, spaces, commas?
+The default value for this list is "reno" plus the default setting of
+.IR tcp_congestion_control .
+.TP
 .IR tcp_app_win  " (integer; default: 31)"
 This variable defines how many
 bytes of the TCP window are reserved for buffering