diff --git a/sys/net/if_stf.h b/sys/net/if_stf.h
index 26c8f2f04e00..8416558d92b1 100644
--- a/sys/net/if_stf.h
+++ b/sys/net/if_stf.h
@@ -1,46 +1,48 @@
 /*-
  * Copyright (C) 2000 WIDE Project.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3. Neither the name of the project nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #ifndef _NET_IF_STF_H_
 #define _NET_IF_STF_H_
 
+#include <netinet/in.h>
+
 struct stfv4args {
 	struct in_addr srcv4_addr;	/* Our IPv4 src/WAN address */
 	struct in_addr braddr;		/* The border relay IPv4 address */
 	int v4_prefixlen;		/* The length of the IPv4 prefix. (I.e.
 					   the number of bits of the IPv4
 					   address not encoded in the IPv6
 					   address. */
 };
 
 #define STF6RD_SV4NET	1
 #define STF6RD_GV4NET	2
 #define STF6RD_SBR	3
 
 #endif /* _NET_IF_STF_H_ */