diff --git a/src/Makefile.am b/src/Makefile.am
index 5d8343c..8606646 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,6 +1,7 @@
 SUBDIRS = \
 	core \
 	vty \
+	isdn \
 	codec \
 	gsm \
 	coding \