diff --git a/sys/netinet6/ip6_ipsec.c b/sys/netinet6/ip6_ipsec.c
index 73b9efe6dba0..5d0dea56cea0 100644
--- a/sys/netinet6/ip6_ipsec.c
+++ b/sys/netinet6/ip6_ipsec.c
@@ -313,6 +313,7 @@ ip6_ipsec_output(struct mbuf **m, struct inpcb *inp, int *flags, int *error,
 	return 0;
 }
 
+#if 0
 /*
  * Compute the MTU for a forwarded packet that gets IPSEC encapsulated.
  * Called from ip_forward().
@@ -328,16 +329,15 @@ ip6_ipsec_mtu(struct mbuf *m)
 	 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
 	 * XXX quickhack!!!
 	 */
+#ifdef IPSEC
 	struct secpolicy *sp = NULL;
 	int ipsecerror;
 	int ipsechdr;
 	struct route *ro;
-#ifdef IPSEC
 	sp = ipsec_getpolicybyaddr(m,
 				   IPSEC_DIR_OUTBOUND,
 				   IP_FORWARDING,
 				   &ipsecerror);
-#endif /* IPSEC */
 	if (sp != NULL) {
 		/* count IPsec header size */
 		ipsechdr = ipsec4_hdrsiz(m,
@@ -360,10 +360,10 @@ ip6_ipsec_mtu(struct mbuf *m)
 				mtu -= ipsechdr;
 			}
 		}
-#ifdef IPSEC
 		KEY_FREESP(&sp);
-#endif /* IPSEC */
 	}
+#endif /* IPSEC */
+	/* XXX else case missing. */
 	return mtu;
 }
-
+#endif
diff --git a/sys/netinet6/ip6_ipsec.h b/sys/netinet6/ip6_ipsec.h
index a02481156a4e..86d1b0050c25 100644
--- a/sys/netinet6/ip6_ipsec.h
+++ b/sys/netinet6/ip6_ipsec.h
@@ -35,7 +35,9 @@
 int	ip6_ipsec_filtertunnel(struct mbuf *);
 int	ip6_ipsec_fwd(struct mbuf *);
 int	ip6_ipsec_input(struct mbuf *, int);
-int	ip6_ipsec_mtu(struct mbuf *);
 int	ip6_ipsec_output(struct mbuf **, struct inpcb *, int *, int *,
 	    struct ifnet **, struct secpolicy **sp);
+#if 0
+int	ip6_ipsec_mtu(struct mbuf *);
+#endif
 #endif