diff --git a/build-aux/Makefile.am b/build-aux/Makefile.am
index 3df64bb4..f2d7fbbb 100644
--- a/build-aux/Makefile.am
+++ b/build-aux/Makefile.am
@@ -1,28 +1,30 @@
 #
 # Copyright (C) 2018 Red Hat, Inc.  All rights reserved.
 #
 # Authors: Fabio M. Di Nitto <fabbione@kronosnet.org>
 #
 # This software licensed under GPL-2.0+, LGPL-2.0+
 #
 
 MAINTAINERCLEANFILES	= Makefile.in
 
 include $(top_srcdir)/build-aux/check.mk
 
 EXTRA_DIST	= check.mk gitlog-to-changelog git-version-gen \
 		  knet_valgrind_helgrind.supp knet_valgrind_memcheck.supp \
 		  release.mk update-copyright.sh
 
+# Avoid Automake warnings about overriding these user variables.
+# Programs in this directory are used during the build only.
+AUTOMAKE_OPTIONS = -Wno-gnu
 EXEEXT=$(BUILD_EXEEXT)
+CC=$(CC_FOR_BUILD)
+CFLAGS=$(CFLAGS_FOR_BUILD)
+CPPFLAGS=$(CPPFLAGS_FOR_BUILD)
+LDFLAGS=$(LDFLAGS_FOR_BUILD)
 
 noinst_PROGRAMS	= doxyxml
 
-$(doxyxml_OBJECTS) : CC=$(CC_FOR_BUILD)
-$(doxyxml_OBJECTS) : CFLAGS=$(CFLAGS_FOR_BUILD)
-$(doxyxml_OBJECTS) : CPPFLAGS=$(CPPFLAGS_FOR_BUILD)
-
 doxyxml_SOURCES = doxyxml.c
 doxyxml_CFLAGS = $(AM_CFLAGS) $(libqb_BUILD_CFLAGS) $(libxml_BUILD_CFLAGS)
 doxyxml_LDADD = $(libqb_BUILD_LIBS) $(libxml_BUILD_LIBS)
-doxyxml_LINK = $(CC_FOR_BUILD) $(doxyxml_CFLAGS) $(CFLAGS_FOR_BUILD) $(AM_LDFLAGS) $(LDFLAGS_FOR_BUILD) -o $@