diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 277ad11e..77296e33 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -8,7 +8,7 @@ snes9x_gtk_CXXFLAGS = -fno-exceptions -fno-rtti
 endif
 noinst_LIBRARIES =
 
-INCLUDES = -I../apu/bapu -I$(top_srcdir) -I.. -DSNES9XLOCALEDIR=\""$(snes9xlocaledir)"\"
+AM_CPPFLAGS = -I../apu/bapu -I$(top_srcdir) -I.. -DSNES9XLOCALEDIR=\""$(snes9xlocaledir)"\"
 
 CLEANFILES = \
     src/gtk_snes9x_ui.cpp \