diff --git a/lib/Modules b/lib/Modules
index ba743dae..b347aa21 100644
--- a/lib/Modules
+++ b/lib/Modules
@@ -2,10 +2,13 @@ birdlib.h
 bitops.c
 bitops.h
 ip.h
-ipv4.c
-ipv4.h
+#ifdef CONFIG_IPV6
 ipv6.c
 ipv6.h
+#else
+ipv4.c
+ipv4.h
+#endif
 lists.c
 lists.h
 md5.c
diff --git a/lib/ipv6.c b/lib/ipv6.c
index 2d01e839..e612af72 100644
--- a/lib/ipv6.c
+++ b/lib/ipv6.c
@@ -6,11 +6,7 @@
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
 
-#ifdef IPV6
-
 #include "nest/bird.h"
 #include "lib/ip.h"
 
 #error "Ought to implement these."
-
-#endif
diff --git a/lib/ipv6.h b/lib/ipv6.h
index b8d2e9f5..35d8e29d 100644
--- a/lib/ipv6.h
+++ b/lib/ipv6.h
@@ -6,8 +6,8 @@
  *	Can be freely distributed and used under the terms of the GNU GPL.
  */
 
-#ifndef _BIRD_IPV4_H_
-#define _BIRD_IPV4_H_
+#ifndef _BIRD_IPV6_H_
+#define _BIRD_IPV6_H_
 
 #include <netinet/in.h>
 #include <string.h>