diff --git a/SDLWrapper/Cursor.h b/SDLWrapper/Cursor.h
index b1b381d..6b45469 100644
--- a/SDLWrapper/Cursor.h
+++ b/SDLWrapper/Cursor.h
@@ -3,6 +3,7 @@
 #include "_SystemCursorType.h"
 #include "Point.h"
 #include "Surface.h"
+#include "__Plugin.h"
 #include "begin_code.h"
 class Cursor
 {
@@ -26,5 +27,7 @@ private:
     void _set_no_delete(SDL_Cursor*);
     SDL_Cursor* _get();
     void _clear();
+
+    friend class _internal::Plugin;
 };
 #include "end_code.h"
diff --git a/SDLWrapper/Font.h b/SDLWrapper/Font.h
index d2d9a24..1587746 100644
--- a/SDLWrapper/Font.h
+++ b/SDLWrapper/Font.h
@@ -7,6 +7,7 @@
 #include "Texture.h"
 #include "Renderer.h"
 #include <vector>
+#include "__Plugin.h"
 #include "begin_code.h"
 class Font
 {
@@ -118,5 +119,7 @@ private:
     void _set(TTF_Font*);
     void _clear();
     TTF_Font* _get() const;
+
+    friend class _internal::Plugin;
 };
 #include "end_code.h"
diff --git a/SDLWrapper/Music.h b/SDLWrapper/Music.h
index 7966886..aebc972 100644
--- a/SDLWrapper/Music.h
+++ b/SDLWrapper/Music.h
@@ -5,6 +5,7 @@
 #include "ErrorViewer.h"
 #include "Audio.h"
 #include "__Noncopyable.h"
+#include "__Plugin.h"
 #include "begin_code.h"
 /// Forward Declaration
 class Music
@@ -19,7 +20,9 @@ private:
     void _set(Mix_Music*);
     void _clear();
     Mix_Music* _get() const;
+
     friend class MusicPlayer;
+    friend class _internal::Plugin;
 };
 
 class MusicPlayer : public AudioPlayer, public NonCopyable
diff --git a/SDLWrapper/RWOP.h b/SDLWrapper/RWOP.h
index 0dd8418..6c0530a 100644
--- a/SDLWrapper/RWOP.h
+++ b/SDLWrapper/RWOP.h
@@ -3,6 +3,7 @@
 #include <cstdio>
 #include <string>
 #include <memory>
+#include "__Plugin.h"
 #include "begin_code.h"
 class RWOP
 {
@@ -22,5 +23,7 @@ private:
     void _set(SDL_RWops*);
     friend class Surface;
     friend class Renderer;
+
+    friend class _internal::Plugin;
 };
 #include "end_code.h"
diff --git a/SDLWrapper/Renderer.h b/SDLWrapper/Renderer.h
index b26084b..be95dfc 100644
--- a/SDLWrapper/Renderer.h
+++ b/SDLWrapper/Renderer.h
@@ -5,6 +5,7 @@
 #include "Window.h"
 #include "Surface.h"
 #include "Texture.h"
+#include "__Plugin.h"
 #include <initializer_list>
 #include "begin_code.h"
 class Renderer
@@ -145,5 +146,7 @@ private:
     void _set(SDL_Renderer*);
     void _clear();
     SDL_Renderer* _get() const;
+
+    friend class _internal::Plugin;
 };
 #include "end_code.h"
diff --git a/SDLWrapper/Sound.h b/SDLWrapper/Sound.h
index b1f677c..3ab2e48 100644
--- a/SDLWrapper/Sound.h
+++ b/SDLWrapper/Sound.h
@@ -4,6 +4,7 @@
 #include <string>
 #include "Audio.h"
 #include "ErrorViewer.h"
+#include "__Plugin.h"
 #include "begin_code.h"
 class Sound
 {
@@ -19,6 +20,7 @@ private:
     Mix_Chunk* _get() const;
 
     friend class Channel;
+    friend class _internal::Plugin;
 };
 
 class Channel
diff --git a/SDLWrapper/Surface.h b/SDLWrapper/Surface.h
index a83fcf6..3fce1dc 100644
--- a/SDLWrapper/Surface.h
+++ b/SDLWrapper/Surface.h
@@ -5,6 +5,7 @@
 #include "Point.h"
 #include "RWOP.h"
 #include "ErrorViewer.h"
+#include "__Plugin.h"
 #include "begin_code.h"
 class Surface
 {
@@ -81,6 +82,8 @@ private:
     friend class Renderer;
     friend class Font;
     friend class Cursor;
+
+    friend class _internal::Plugin;
 };
 
 #include "end_code.h"
diff --git a/SDLWrapper/Texture.h b/SDLWrapper/Texture.h
index b023244..3c0dcfc 100644
--- a/SDLWrapper/Texture.h
+++ b/SDLWrapper/Texture.h
@@ -4,6 +4,7 @@
 #include "RGBA.h"
 #include "ColorMode.h"
 #include "_BlendMode.h"
+#include "__Plugin.h"
 #include <memory>
 #include "begin_code.h"
 
@@ -40,6 +41,8 @@ private:
     SDL_Texture* _get() const;
     Rect _rect;
     friend class Renderer;
+
+    friend class _internal::Plugin;
 };
 
 #include "end_code.h"
diff --git a/SDLWrapper/Window.h b/SDLWrapper/Window.h
index 4e1a9e9..644bd0f 100644
--- a/SDLWrapper/Window.h
+++ b/SDLWrapper/Window.h
@@ -5,6 +5,7 @@
 #include "ErrorViewer.h"
 #include "MessageBox.h"
 #include "Surface.h"
+#include "__Plugin.h"
 #include "begin_code.h"
 class Window
 {
@@ -62,5 +63,6 @@ private:
     SDL_Window* _get() const;
 
     friend class Renderer;
+    friend class _internal::Plugin;
 };
 #include "end_code.h"