diff --git a/olcNoiseMaker.h b/olcNoiseMaker.h
index 2953f31..69ad751 100644
--- a/olcNoiseMaker.h
+++ b/olcNoiseMaker.h
@@ -229,7 +229,7 @@ class olcNoiseMaker
 	}
 
 	// Static wrapper for sound card handler
-	static void CALLBACK waveOutProcWrap(HWAVEOUT hWaveOut, UINT uMsg, DWORD dwInstance, DWORD dwParam1, DWORD dwParam2)
+	static void CALLBACK waveOutProcWrap(HWAVEOUT hWaveOut, UINT uMsg, DWORD_PTR dwInstance, DWORD dwParam1, DWORD dwParam2)
 	{
 		((olcNoiseMaker*)dwInstance)->waveOutProc(hWaveOut, uMsg, dwParam1, dwParam2);
 	}