diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8a086d0..1fe28c7 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -13,7 +13,7 @@
 	testcommands.in \
 	testcommands.refout
 
-INCLUDES = @INCLUDES@ -I.. -I$(top_srcdir) -I$(top_srcdir)/lib -I$(top_builddir)/lib
+AM_CPPFLAGS = -I.. -I$(top_srcdir) -I$(top_srcdir)/lib -I$(top_builddir)/lib
 DEFS = @DEFS@ $(LOCAL_OPTS) -DSYSCONFDIR=\"$(sysconfdir)/\"
 
 AM_CFLAGS = $(PICFLAGS)