diff --git a/sys/conf/files b/sys/conf/files
index 0ad346bb2a37..1a2fbc305101 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -136,7 +136,9 @@ net/bpf_filter.c	optional bpfilter
 net/if.c		standard
 net/if_ethersubr.c	optional ether
 net/if_loop.c		optional loop
+net/if_ppp.c		optional ppp
 net/if_sl.c		optional sl
+net/pppcompress.c	optional ppp
 net/radix.c		standard
 net/raw_cb.c		standard
 net/raw_usrreq.c	standard