--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -35,6 +35,7 @@
 
 /* Do not check the TCP window for incoming packets  */
 static int nf_ct_tcp_no_window_check __read_mostly = 1;
+EXPORT_SYMBOL_GPL(nf_ct_tcp_no_window_check);
 
 /* "Be conservative in what you do,
     be liberal in what you accept from others."