diff --git a/Makefile.am b/Makefile.am
index ad12c0f1..f24cac7c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -528,7 +528,7 @@ AM_CFLAGS = @DBUS_CFLAGS@ @GLIB_CFLAGS@ @USB_CFLAGS@ \
 					-DOFONO_PLUGIN_BUILTIN \
 					-DPLUGINDIR=\""$(build_plugindir)"\"
 
-INCLUDES = -I$(builddir)/include -I$(builddir)/src -I$(srcdir)/src \
+AM_CPPFLAGS = -I$(builddir)/include -I$(builddir)/src -I$(srcdir)/src \
 			-I$(srcdir)/gdbus -I$(srcdir)/gisi -I$(srcdir)/gatchat \
 			-I$(srcdir)/btio