diff --git a/usr.sbin/ppp/ipv6cp.c b/usr.sbin/ppp/ipv6cp.c
index b126b0d078f7..6c52d524c4c0 100644
--- a/usr.sbin/ppp/ipv6cp.c
+++ b/usr.sbin/ppp/ipv6cp.c
@@ -78,6 +78,7 @@
 #include "async.h"
 #include "physical.h"
 #include "probe.h"
+#include "systems.h"
 
 
 #ifndef NOINET6