diff --git a/openbsc/src/Makefile.am b/openbsc/src/Makefile.am
index aa50b8c..e18c35e 100644
--- a/openbsc/src/Makefile.am
+++ b/openbsc/src/Makefile.am
@@ -12,7 +12,8 @@
 		trau_frame.c trau_mux.c paging.c e1_config.c e1_input.c tlv_parser.c \
 		input/misdn.c input/ipaccess.c signal.c gsm_utils.c talloc.c \
 		talloc_ctx.c system_information.c bitvec.c rest_octets.c \
-		rtp_proxy.c statistics.c bts_siemens_bs11.c bts_ipaccess_nanobts.c
+		rtp_proxy.c statistics.c bts_siemens_bs11.c bts_ipaccess_nanobts.c \
+		bts_unknown.c
 
 libmsc_a_SOURCES = gsm_subscriber.c db.c telnet_interface.c \
 		mncc.c gsm_04_08.c gsm_04_11.c transaction.c \