diff --git a/ggsn/Makefile.am b/ggsn/Makefile.am
index 761c820..c15f767 100644
--- a/ggsn/Makefile.am
+++ b/ggsn/Makefile.am
@@ -8,5 +8,5 @@
 
 #ggsn_DEPENDENCIES = ../gtp/libgtp.la
 
-ggsn_SOURCES = ggsn.c tun.c tun.h cmdline.c cmdline.h ippool.h ippool.c syserr.h syserr.c lookup.c
+ggsn_SOURCES = ggsn.c tun.c tun.h cmdline.c cmdline.h ippool.h ippool.c syserr.h syserr.c lookup.c lookup.h