diff --git a/Makefile.am b/Makefile.am
index ab2aad921..b3663baf7 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,7 +1,22 @@
 ACLOCAL_AMFLAGS = -I m4
 
 AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
-SUBDIRS = include src src/vty src/codec src/gsm src/coding src/gb src/ctrl src/sim src/pseudotalloc src/usb utils tapset tests
+SUBDIRS = \
+	include \
+	src \
+	src/vty \
+	src/codec \
+	src/gsm \
+	src/coding \
+	src/gb \
+	src/ctrl \
+	src/sim \
+	src/pseudotalloc \
+	src/usb \
+	utils \
+	tapset \
+	tests \
+	$(NULL)
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = libosmocore.pc libosmocodec.pc libosmovty.pc libosmogsm.pc \