diff --git a/openbsc/src/libtrau/Makefile.am b/openbsc/src/libtrau/Makefile.am
index 0fe3a53..46becd6 100644
--- a/openbsc/src/libtrau/Makefile.am
+++ b/openbsc/src/libtrau/Makefile.am
@@ -1,7 +1,31 @@
-AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
-AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOVTY_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(LIBOSMONETIF_CFLAGS) $(COVERAGE_CFLAGS)
-AM_LDFLAGS = $(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(LIBOSMOABIS_LIBS) $(COVERAGE_LDFLAGS)
+AM_CPPFLAGS = \
+	$(all_includes) \
+	-I$(top_srcdir)/include \
+	-I$(top_builddir) \
+	$(NULL)
 
-noinst_LIBRARIES = libtrau.a
+AM_CFLAGS = \
+	-Wall \
+	$(LIBOSMOCORE_CFLAGS) \
+	$(LIBOSMOVTY_CFLAGS) \
+	$(LIBOSMOABIS_CFLAGS) \
+	$(LIBOSMONETIF_CFLAGS) \
+	$(COVERAGE_CFLAGS) \
+	$(NULL)
 
-libtrau_a_SOURCES = rtp_proxy.c trau_mux.c trau_upqueue.c
+AM_LDFLAGS = \
+	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOGSM_LIBS) \
+	$(LIBOSMOABIS_LIBS) \
+	$(COVERAGE_LDFLAGS) \
+	$(NULL)
+
+noinst_LIBRARIES = \
+	libtrau.a \
+	$(NULL)
+
+libtrau_a_SOURCES = \
+	rtp_proxy.c \
+	trau_mux.c \
+	trau_upqueue.c \
+	$(NULL)