https://bugs.gentoo.org/attachment.cgi?id=278091&action=diff&context=patch&collapsed=&headers=1&format=raw
https://bugs.gentoo.org/show_bug.cgi?id=372953

--- a/gtk/Makefile.am	
+++ a/gtk/Makefile.am	
@@ -32,7 +32,7 @@ endif
 endif
 endif
 
-INCLUDES =						\
+INCLUDES_COMMON =					\
 	-DG_LOG_DOMAIN=\"Gtk\"				\
 	-DGTK_LIBDIR=\"$(libdir)\"			\
 	-DGTK_DATADIR=\"$(datadir)\"			\
@@ -52,10 +52,17 @@ INCLUDES =						\
 	-DGTK_FILE_SYSTEM_ENABLE_UNSUPPORTED		\
 	-DGTK_PRINT_BACKEND_ENABLE_UNSUPPORTED		\
 	$(GTK_DEBUG_FLAGS)				\
-	$(GTK_DEP_CFLAGS)				\
+	$(GTK_DEP_CFLAGS)
+
+INCLUDES= 						\
+	$(INCLUDES_COMMON)				\
 	$(gtk_clipboard_dnd_c_sources_CFLAGS)		\
 	$(INCLUDED_IMMODULE_DEFINE)
 
+INCLUDES_GIR=						\
+	$(INCLUDES_COMMON)				\
+	$(INCLUDED_IMMODULE_DEFINE)
+
 gtarget=$(gdktarget)
 
 if PLATFORM_WIN32
@@ -999,7 +1006,7 @@ Gtk_2_0_gir_SCANNERFLAGS += --add-include-path=$(top_builddir)/gdk/x11
 endif
 Gtk_2_0_gir_INCLUDES = Atk-1.0 Gdk-2.0
 Gtk_2_0_gir_CFLAGS = \
-		$(INCLUDES) \
+		$(INCLUDES_GIR) \
 		-UGDK_DISABLE_DEPRECATED \
 		-UGTK_DISABLE_DEPRECATED \
 		-DGTK_TEXT_USE_INTERNAL_UNSUPPORTED_API