diff --git a/gnulib-tests/Makefile.am b/gnulib-tests/Makefile.am
index 3085f63..ae4e035 100644
--- a/gnulib-tests/Makefile.am
+++ b/gnulib-tests/Makefile.am
@@ -1,4 +1,3 @@
-AM_CFLAGS =
-include gnulib.mk
+AM_CFLAGS = $(GNULIB_TEST_WARN_CFLAGS) $(WERROR_CFLAGS)
 
-AM_CFLAGS += $(GNULIB_TEST_WARN_CFLAGS) $(WERROR_CFLAGS)
+include gnulib.mk