diff --git a/share/man/man4/ng_netflow.4 b/share/man/man4/ng_netflow.4
index 689e9a6f3b4..0dd26cce6a3 100644
--- a/share/man/man4/ng_netflow.4
+++ b/share/man/man4/ng_netflow.4
@@ -30,6 +30,10 @@
 .Sh NAME
 .Nm ng_netflow
 .Nd Cisco's NetFlow implementation
+.Sh SYNOPSIS
+.In sys/types.h
+.In netinet/in.h
+.In netgraph/netflow/ng_netflow.h
 .Sh DESCRIPTION
 The
 .Nm