diff --git a/openbsc/src/libiu/Makefile.am b/openbsc/src/libiu/Makefile.am
index 1968d3e..e5f9e27 100644
--- a/openbsc/src/libiu/Makefile.am
+++ b/openbsc/src/libiu/Makefile.am
@@ -1,10 +1,28 @@
-AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include -I$(top_builddir)
-AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOVTY_CFLAGS) \
-	$(LIBOSMOGSM_CFLAGS) $(LIBOSMOABIS_CFLAGS) $(COVERAGE_CFLAGS) $(LIBCRYPTO_CFLAGS) \
+AM_CPPFLAGS = \
+	$(all_includes) \
+	-I$(top_srcdir)/include \
+	-I$(top_builddir) \
+	$(NULL)
+
+AM_CFLAGS = \
+	-Wall \
+	$(COVERAGE_CFLAGS) \
+	$(LIBCRYPTO_CFLAGS) \
 	$(LIBASN1C_CFLAGS) \
-	$(LIBOSMOSIGTRAN_CFLAGS) $(LIBOSMORANAP_CFLAGS)
+	$(LIBOSMOCORE_CFLAGS) \
+	$(LIBOSMOVTY_CFLAGS) \
+	$(LIBOSMOGSM_CFLAGS) \
+	$(LIBOSMOABIS_CFLAGS) \
+	$(LIBOSMOSIGTRAN_CFLAGS) \
+	$(LIBOSMORANAP_CFLAGS) \
+	$(NULL)
 
-noinst_LIBRARIES = libiu.a
+noinst_LIBRARIES = \
+	libiu.a \
+	$(NULL)
 
-libiu_a_SOURCES = iu.c iu_vty.c
+libiu_a_SOURCES = \
+	iu.c \
+	iu_vty.c \
+	$(NULL)