--- Source/WTF/wtf/gobject/GRefPtr.h	2021-04-22 00:32:56.644133999 +0900
+++ Source/WTF/wtf/gobject/GRefPtr.h	2021-04-22 00:33:57.755315484 +0900
@@ -25,11 +25,11 @@
 
 #if USE(GLIB)
 
+#include <glib-object.h>
+
 #include <wtf/RefPtr.h>
 #include <algorithm>
 
-extern "C" void g_object_unref(gpointer);
-extern "C" gpointer g_object_ref_sink(gpointer);
 
 namespace WTF {
 
--- GNUmakefile.in	2021-04-22 00:35:24.846905490 +0900
+++ GNUmakefile.in	2021-04-22 00:42:04.543194694 +0900
@@ -96250,8 +96250,8 @@
 	@true
 
 stamp-webkitmarshal.cpp: $(WEBKIT_MARSHAL_LIST)
-	$(AM_V_GEN) echo "extern \"C\" {" > $(GENSOURCES_WEBKIT)/webkitmarshal.cpp && \
-	$(GLIB_GENMARSHAL) --prefix=webkit_marshal $(WEBKIT_MARSHAL_LIST) --body >> $(GENSOURCES_WEBKIT)/webkitmarshal.cpp && \
+	$(AM_V_GEN)	$(GLIB_GENMARSHAL) --prefix=webkit_marshal $(WEBKIT_MARSHAL_LIST) --body >> $(GENSOURCES_WEBKIT)/webkitmarshal.cpp && \
+	sed -i '1,10s/#ifdef/extern "C" {\n#ifdef/gm' $(GENSOURCES_WEBKIT)/webkitmarshal.cpp && \
 	echo '}' >> $(GENSOURCES_WEBKIT)/webkitmarshal.cpp && \
 	echo timestamp > $(@F)