diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 3173d12..3882db1 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -108,6 +108,8 @@
 
 extern struct list_head net_namespace_list;
 
+extern struct net *get_net_ns_by_pid(pid_t pid);
+
 #ifdef CONFIG_NET_NS
 extern void __put_net(struct net *net);