diff --git a/miniwin/miniwin/include/miniwin_d3drm.h b/miniwin/miniwin/include/miniwin_d3drm.h
index e8b33522..8fe98156 100644
--- a/miniwin/miniwin/include/miniwin_d3drm.h
+++ b/miniwin/miniwin/include/miniwin_d3drm.h
@@ -313,7 +313,7 @@ struct IDirect3DRMDevice : virtual public IDirect3DRMObject {
 	virtual HRESULT GetShades() = 0;
 	virtual HRESULT SetQuality(D3DRMRENDERQUALITY quality) = 0;
 	virtual D3DRMRENDERQUALITY GetQuality() = 0;
-	virtual HRESULT SetDither(int dither) = 0;
+	virtual HRESULT SetDither(BOOL dither) = 0;
 	virtual BOOL GetDither() = 0;
 	virtual HRESULT SetTextureQuality(D3DRMTEXTUREQUALITY quality) = 0;
 	virtual D3DRMTEXTUREQUALITY GetTextureQuality() = 0;
diff --git a/miniwin/miniwin/src/include/miniwin_d3drmdevice_p.h b/miniwin/miniwin/src/include/miniwin_d3drmdevice_p.h
index faa3b6e0..aabc0633 100644
--- a/miniwin/miniwin/src/include/miniwin_d3drmdevice_p.h
+++ b/miniwin/miniwin/src/include/miniwin_d3drmdevice_p.h
@@ -16,7 +16,7 @@ struct Direct3DRMDevice2Impl : public Direct3DRMObjectBase<IDirect3DRMDevice2> {
 	HRESULT GetShades() override;
 	HRESULT SetQuality(D3DRMRENDERQUALITY quality) override;
 	D3DRMRENDERQUALITY GetQuality() override;
-	HRESULT SetDither(int dither) override;
+	HRESULT SetDither(BOOL dither) override;
 	BOOL GetDither() override;
 	HRESULT SetTextureQuality(D3DRMTEXTUREQUALITY quality) override;
 	D3DRMTEXTUREQUALITY GetTextureQuality() override;
diff --git a/miniwin/miniwin/src/miniwin_d3drmdevice.cpp b/miniwin/miniwin/src/miniwin_d3drmdevice.cpp
index b9125cc8..d97433b7 100644
--- a/miniwin/miniwin/src/miniwin_d3drmdevice.cpp
+++ b/miniwin/miniwin/src/miniwin_d3drmdevice.cpp
@@ -71,7 +71,7 @@ D3DRMRENDERQUALITY Direct3DRMDevice2Impl::GetQuality()
 	return D3DRMRENDERQUALITY::GOURAUD;
 }
 
-HRESULT Direct3DRMDevice2Impl::SetDither(int dither)
+HRESULT Direct3DRMDevice2Impl::SetDither(BOOL dither)
 {
 	MINIWIN_NOT_IMPLEMENTED();
 	return DD_OK;