diff --git a/openbsc/tests/gsm0408/Makefile.am b/openbsc/tests/gsm0408/Makefile.am
index 12b0142..b000c08 100644
--- a/openbsc/tests/gsm0408/Makefile.am
+++ b/openbsc/tests/gsm0408/Makefile.am
@@ -1,4 +1,4 @@
-INCLUDES = $(all_includes) -I$(top_srcdir)/include
+AM_CPPFLAGS = $(all_includes) -I$(top_srcdir)/include
 AM_CFLAGS=-Wall $(LIBOSMOCORE_CFLAGS) $(LIBOSMOGSM_CFLAGS) $(LIBOSMOABIS_CFLAGS)
 noinst_PROGRAMS = gsm0408_test