diff --git a/binding-mri/binding-util.h b/binding-mri/binding-util.h
index 8bc4c93..2c9fcea 100644
--- a/binding-mri/binding-util.h
+++ b/binding-mri/binding-util.h
@@ -24,8 +24,6 @@
 
 #include "./ruby/ruby.h"
 
-#define PRIV_IV "priv"
-
 enum RbException
 {
 	RGSS = 0,
@@ -68,6 +66,12 @@ void initType(rb_data_type_struct &type,
               const char *name,
               void (*freeInst)(void*));
 
+template<rb_data_type_t *rbType>
+static VALUE classAllocate(VALUE klass)
+{
+	return rb_data_typed_object_alloc(klass, 0, rbType);
+}
+
 template<class C>
 static void freeInstance(void *inst)
 {
@@ -80,24 +84,21 @@ template<class C>
 static inline C *
 getPrivateData(VALUE self)
 {
-	VALUE priv = rb_iv_get(self, PRIV_IV);
-	return static_cast<C*>(RTYPEDDATA_DATA(priv));
+	return static_cast<C*>(RTYPEDDATA_DATA(self));
 }
 
 template<class C>
 static inline C *
 getPrivateDataCheck(VALUE self, const rb_data_type_struct &type)
 {
-	VALUE priv = rb_iv_get(self, PRIV_IV);
-	void *obj = rb_check_typeddata(priv, &type);
+	void *obj = rb_check_typeddata(self, &type);
 	return static_cast<C*>(obj);
 }
 
 static inline void
-setPrivateData(VALUE self, void *p, const rb_data_type_struct &type)
+setPrivateData(VALUE self, void *p)
 {
-	VALUE priv = rb_data_typed_object_alloc(rb_cData, p, &type);
-	rb_iv_set(self, PRIV_IV, priv);
+	RTYPEDDATA_DATA(self) = p;
 }
 
 inline VALUE
@@ -106,7 +107,7 @@ wrapObject(void *p, const rb_data_type_struct &type)
 	VALUE klass = rb_const_get(rb_cObject, rb_intern(type.wrap_struct_name));
 	VALUE obj = rb_obj_alloc(klass);
 
-	setPrivateData(obj, p, type);
+	setPrivateData(obj, p);
 
 	return obj;
 }
@@ -160,7 +161,7 @@ _rb_define_module_function(VALUE module, const char *name, RubyMethod func)
 
 template<class C>
 static inline VALUE
-objectLoad(int argc, VALUE *argv, VALUE self, rb_data_type_struct &type)
+objectLoad(int argc, VALUE *argv, VALUE self)
 {
 	const char *data;
 	int dataLen;
@@ -172,7 +173,7 @@ objectLoad(int argc, VALUE *argv, VALUE self, rb_data_type_struct &type)
 
 	GUARD_EXC( c = C::deserialize(data, dataLen); );
 
-	setPrivateData(obj, c, type);
+	setPrivateData(obj, c);
 
 	return obj;
 }
@@ -192,7 +193,7 @@ rb_bool_new(bool value)
 #define MARSH_LOAD_FUN(Typ) \
 	RB_METHOD(Typ##Load) \
 	{ \
-		return objectLoad<Typ>(argc, argv, self, Typ##Type); \
+		return objectLoad<Typ>(argc, argv, self); \
 	}
 
 #define CLONE_FUNC(Klass) \
@@ -213,7 +214,7 @@ rb_bool_new(bool value)
 		Klass *k = getPrivateData<Klass>(self); \
 		VALUE dupObj = rb_obj_clone(self); \
 		Klass *dupK = new Klass(*k); \
-		setPrivateData(dupObj, dupK, Klass##Type); \
+		setPrivateData(dupObj, dupK); \
 		return dupObj; \
 	}
 
diff --git a/binding-mri/bitmap-binding.cpp b/binding-mri/bitmap-binding.cpp
index 7243608..fd28c1a 100644
--- a/binding-mri/bitmap-binding.cpp
+++ b/binding-mri/bitmap-binding.cpp
@@ -51,7 +51,7 @@ RB_METHOD(bitmapInitialize)
 		GUARD_EXC( b = new Bitmap(width, height); )
 	}
 
-	setPrivateData(self, b, BitmapType);
+	setPrivateData(self, b);
 
 	/* Wrap properties */
 	Font *font = new Font();
@@ -300,6 +300,7 @@ bitmapBindingInit()
 	INIT_TYPE(Bitmap);
 
 	VALUE klass = rb_define_class("Bitmap", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&BitmapType>);
 
 	disposableBindingInit<Bitmap>(klass);
 
diff --git a/binding-mri/etc-binding.cpp b/binding-mri/etc-binding.cpp
index f57e3c7..226ad24 100644
--- a/binding-mri/etc-binding.cpp
+++ b/binding-mri/etc-binding.cpp
@@ -84,7 +84,7 @@ EQUAL_FUN(Rect)
 		param_type p1, p2, p3, p4 = last_param_def; \
 		rb_get_args(argc, argv, param_t_s, &p1, &p2, &p3, &p4, RB_ARG_END); \
 		Klass *k = new Klass(p1, p2, p3, p4); \
-		setPrivateData(self, k, Klass##Type); \
+		setPrivateData(self, k); \
 		return self; \
 	}
 
@@ -156,6 +156,7 @@ CLONE_FUN(Rect)
 { \
 	INIT_TYPE(Klass); \
 	klass = rb_define_class(#Klass, rb_cObject); \
+	rb_define_alloc_func(klass, classAllocate<&Klass##Type>); \
 	rb_define_class_method(klass, "_load", Klass##Load); \
 	serializableBindingInit<Klass>(klass); \
 	_rb_define_method(klass, "initialize", Klass##Initialize); \
diff --git a/binding-mri/filesystem-binding.cpp b/binding-mri/filesystem-binding.cpp
index 7294b4d..9c691b1 100644
--- a/binding-mri/filesystem-binding.cpp
+++ b/binding-mri/filesystem-binding.cpp
@@ -41,7 +41,7 @@ fileIntForPath(const char *path)
 
 	VALUE obj = rb_obj_alloc(klass);
 
-	setPrivateData(obj, ops, FileIntType);
+	setPrivateData(obj, ops);
 
 	return obj;
 }
@@ -198,6 +198,7 @@ fileIntBindingInit()
 	initType(FileIntType, "FileInt", fileIntFreeInstance);
 
 	VALUE klass = rb_define_class("FileInt", rb_cIO);
+	rb_define_alloc_func(klass, classAllocate<&FileIntType>);
 
 	_rb_define_method(klass, "read", fileIntRead);
 	_rb_define_method(klass, "getbyte", fileIntGetByte);
diff --git a/binding-mri/font-binding.cpp b/binding-mri/font-binding.cpp
index 2db688d..16f830e 100644
--- a/binding-mri/font-binding.cpp
+++ b/binding-mri/font-binding.cpp
@@ -45,7 +45,7 @@ RB_METHOD(fontInitialize)
 
 	Font *f = new Font(name, size);
 
-	setPrivateData(self, f, FontType);
+	setPrivateData(self, f);
 
 	/* Wrap property objects */
 	f->setColor(new Color(*f->getColor()));
@@ -151,6 +151,7 @@ fontBindingInit()
 	INIT_TYPE(Font);
 
 	VALUE klass = rb_define_class("Font", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&FontType>);
 
 	Font::setDefaultColor(new Color(*Font::getDefaultColor()));
 	wrapProperty(klass, Font::getDefaultColor(), "default_color", ColorType);
diff --git a/binding-mri/plane-binding.cpp b/binding-mri/plane-binding.cpp
index f203818..3fdb808 100644
--- a/binding-mri/plane-binding.cpp
+++ b/binding-mri/plane-binding.cpp
@@ -31,7 +31,7 @@ RB_METHOD(planeInitialize)
 {
 	Plane *p = viewportElementInitialize<Plane>(argc, argv, self);
 
-	setPrivateData(self, p, PlaneType);
+	setPrivateData(self, p);
 
 	p->setColor(new Color);
 	p->setTone(new Tone);
@@ -64,6 +64,7 @@ planeBindingInit()
 	INIT_TYPE(Plane);
 
 	VALUE klass = rb_define_class("Plane", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&PlaneType>);
 
 	disposableBindingInit<Plane>     (klass);
 	viewportElementBindingInit<Plane>(klass);
diff --git a/binding-mri/sprite-binding.cpp b/binding-mri/sprite-binding.cpp
index bc62302..e29c6a4 100644
--- a/binding-mri/sprite-binding.cpp
+++ b/binding-mri/sprite-binding.cpp
@@ -33,7 +33,7 @@ RB_METHOD(spriteInitialize)
 {
 	Sprite *s = viewportElementInitialize<Sprite>(argc, argv, self);
 
-	setPrivateData(self, s, SpriteType);
+	setPrivateData(self, s);
 
 	/* Wrap property objects */
 	s->setSrcRect(new Rect);
@@ -75,6 +75,7 @@ spriteBindingInit()
 	INIT_TYPE(Sprite);
 
 	VALUE klass = rb_define_class("Sprite", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&SpriteType>);
 
 	disposableBindingInit     <Sprite>(klass);
 	flashableBindingInit      <Sprite>(klass);
diff --git a/binding-mri/table-binding.cpp b/binding-mri/table-binding.cpp
index 81152dd..8e68690 100644
--- a/binding-mri/table-binding.cpp
+++ b/binding-mri/table-binding.cpp
@@ -34,7 +34,7 @@ RB_METHOD(tableInitialize)
 
 	Table *t = new Table(x, y, z);
 
-	setPrivateData(self, t, TableType);
+	setPrivateData(self, t);
 
 	return self;
 }
@@ -146,6 +146,7 @@ tableBindingInit()
 	INIT_TYPE(Table);
 
 	VALUE klass = rb_define_class("Table", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&TableType>);
 
 	serializableBindingInit<Table>(klass);
 
diff --git a/binding-mri/tilemap-binding.cpp b/binding-mri/tilemap-binding.cpp
index 2b5ad38..aeff10f 100644
--- a/binding-mri/tilemap-binding.cpp
+++ b/binding-mri/tilemap-binding.cpp
@@ -28,7 +28,7 @@
 #include "binding-util.h"
 #include "binding-types.h"
 
-static rb_data_type_struct TilemapAutotilesType;
+rb_data_type_struct TilemapAutotilesType;
 
 RB_METHOD(tilemapAutotilesSet)
 {
@@ -80,7 +80,7 @@ RB_METHOD(tilemapInitialize)
 	/* Construct object */
 	t = new Tilemap(viewport);
 
-	setPrivateData(self, t, TilemapType);
+	setPrivateData(self, t);
 
 	rb_iv_set(self, "viewport", viewportObj);
 
@@ -144,6 +144,7 @@ tilemapBindingInit()
 	initType(TilemapAutotilesType, "TilemapAutotiles", 0);
 
 	VALUE klass = rb_define_class("TilemapAutotiles", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&TilemapAutotilesType>);
 
 	_rb_define_method(klass, "[]=", tilemapAutotilesSet);
 	_rb_define_method(klass, "[]", tilemapAutotilesGet);
@@ -151,6 +152,7 @@ tilemapBindingInit()
 	INIT_TYPE(Tilemap);
 
 	klass = rb_define_class("Tilemap", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&TilemapType>);
 
 	disposableBindingInit<Tilemap>(klass);
 
diff --git a/binding-mri/viewport-binding.cpp b/binding-mri/viewport-binding.cpp
index 2406cc4..47df6be 100644
--- a/binding-mri/viewport-binding.cpp
+++ b/binding-mri/viewport-binding.cpp
@@ -54,7 +54,7 @@ RB_METHOD(viewportInitialize)
 		v = new Viewport(x, y, width, height);
 	}
 
-	setPrivateData(self, v, ViewportType);
+	setPrivateData(self, v);
 
 	/* Wrap property objects */
 	v->setRect(new Rect(*v->getRect()));
@@ -84,6 +84,7 @@ viewportBindingInit()
 	INIT_TYPE(Viewport);
 
 	VALUE klass = rb_define_class("Viewport", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&ViewportType>);
 
 	disposableBindingInit  <Viewport>(klass);
 	flashableBindingInit   <Viewport>(klass);
diff --git a/binding-mri/window-binding.cpp b/binding-mri/window-binding.cpp
index 06402ae..b77c49c 100644
--- a/binding-mri/window-binding.cpp
+++ b/binding-mri/window-binding.cpp
@@ -30,7 +30,7 @@ RB_METHOD(windowInitialize)
 {
 	Window *w = viewportElementInitialize<Window>(argc, argv, self);
 
-	setPrivateData(self, w, WindowType);
+	setPrivateData(self, w);
 
 	w->setCursorRect(new Rect);
 	wrapNilProperty(self, "windowskin");
@@ -78,6 +78,7 @@ windowBindingInit()
 	INIT_TYPE(Window);
 
 	VALUE klass = rb_define_class("Window", rb_cObject);
+	rb_define_alloc_func(klass, classAllocate<&WindowType>);
 
 	disposableBindingInit     <Window>(klass);
 	viewportElementBindingInit<Window>(klass);