bs11_config build fix

diff --git a/src/Makefile.am b/src/Makefile.am
index 643bf67..bda3fd1 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -16,7 +16,8 @@
 bsc_hack_SOURCES = bsc_hack.c vty_interface.c
 bsc_hack_LDADD = libbsc.a libvty.a -ldl -ldbi -lcrypt
 
-bs11_config_SOURCES = bs11_config.c abis_nm.c gsm_data.c msgb.c debug.c select.c timer.c rs232.c tlv_parser.c
+bs11_config_SOURCES = bs11_config.c abis_nm.c gsm_data.c msgb.c debug.c \
+		      select.c timer.c rs232.c tlv_parser.c signal.c
 
 ipaccess_find_SOURCES = ipaccess-find.c select.c timer.c