diff --git a/Makefile b/Makefile
index 319cb87..81540ba 100644
--- a/Makefile
+++ b/Makefile
@@ -13,8 +13,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-SUBDIRS=bsc bsc-nat bts cbc ccid fr fr-net gbproxy ggsn_tests hlr mgw mme msc pcu pgw remsim \
-	sccp selftest sgsn simtrace sip stp sysinfo smlc
+SUBDIRS= \
+	bsc \
+	bsc-nat \
+	bts \
+	cbc \
+	ccid \
+	fr \
+	fr-net \
+	gbproxy \
+	ggsn_tests \
+	hlr \
+	mgw \
+	mme \
+	msc \
+	ns \
+	pcu \
+	pgw \
+	remsim \
+	sccp \
+	selftest \
+	sgsn \
+	simtrace \
+	sip \
+	smlc \
+	stp \
+	sysinfo \
+	$(NULL)
 
 NPROC=$(shell nproc 2>/dev/null)
 ifeq ($(NPROC),)