diff --git a/src/audio.h b/src/audio.h
index 3efc2c0..496dbe4 100644
--- a/src/audio.h
+++ b/src/audio.h
@@ -37,9 +37,6 @@ struct AudioPrivate;
 class Audio
 {
 public:
-	Audio();
-	~Audio();
-
 	void bgmPlay(const char *filename,
 	             int volume = 100,
 	             int pitch = 100
@@ -78,6 +75,11 @@ public:
 #endif
 
 private:
+	Audio();
+	~Audio();
+
+	friend struct SharedStatePrivate;
+
 	AudioPrivate *p;
 };
 
diff --git a/src/graphics.h b/src/graphics.h
index f8b3721..7d3bfb6 100644
--- a/src/graphics.h
+++ b/src/graphics.h
@@ -32,9 +32,6 @@ struct GraphicsPrivate;
 class Graphics
 {
 public:
-	Graphics(RGSSThreadData *data);
-	~Graphics();
-
 	void update();
 	void freeze();
 	void transition(int duration = 8,
@@ -70,6 +67,11 @@ public:
 	void repaintWait(volatile bool *exitCond);
 
 private:
+	Graphics(RGSSThreadData *data);
+	~Graphics();
+
+	friend struct SharedStatePrivate;
+
 	GraphicsPrivate *p;
 };
 
diff --git a/src/input.h b/src/input.h
index c594d5a..7d4c2c9 100644
--- a/src/input.h
+++ b/src/input.h
@@ -47,9 +47,6 @@ public:
 
 	static const int buttonCodeSize;
 
-	Input();
-	~Input();
-
 	void update();
 
 	bool isPressed(int button);
@@ -64,6 +61,11 @@ public:
 	int mouseY();
 
 private:
+	Input();
+	~Input();
+
+	friend struct SharedStatePrivate;
+
 	InputPrivate *p;
 };