diff --git a/inc/ddsurface.h b/inc/ddsurface.h
index 384d616..125c79d 100644
--- a/inc/ddsurface.h
+++ b/inc/ddsurface.h
@@ -29,7 +29,7 @@ HRESULT dds_ReleaseDC(IDirectDrawSurfaceImpl* This, HDC hDC);
 HRESULT dds_SetClipper(IDirectDrawSurfaceImpl* This, IDirectDrawClipperImpl* lpClipper);
 HRESULT dds_SetColorKey(IDirectDrawSurfaceImpl* This, DWORD dwFlags, LPDDCOLORKEY lpColorKey);
 HRESULT dds_SetPalette(IDirectDrawSurfaceImpl* This, IDirectDrawPaletteImpl* lpDDPalette);
-HRESULT dds_Unlock(IDirectDrawSurfaceImpl* This, LPVOID lpRect);
+HRESULT dds_Unlock(IDirectDrawSurfaceImpl* This, LPRECT lpRect);
 HRESULT dds_GetDDInterface(IDirectDrawSurfaceImpl* This, LPVOID* lplpDD);
 void* dds_GetBuffer(IDirectDrawSurfaceImpl* This);
 HRESULT dd_CreateSurface(IDirectDrawImpl* This, LPDDSURFACEDESC2 lpDDSurfaceDesc, IDirectDrawSurfaceImpl** lpDDSurface, IUnknown FAR* unkOuter);
diff --git a/src/ddsurface.c b/src/ddsurface.c
index 3403be7..0ad1e12 100644
--- a/src/ddsurface.c
+++ b/src/ddsurface.c
@@ -1162,7 +1162,7 @@ HRESULT dds_SetPalette(IDirectDrawSurfaceImpl* This, IDirectDrawPaletteImpl* lpD
     return DD_OK;
 }
 
-HRESULT dds_Unlock(IDirectDrawSurfaceImpl* This, LPVOID lpRect)
+HRESULT dds_Unlock(IDirectDrawSurfaceImpl* This, LPRECT lpRect)
 {
     /* Hack for Warcraft II BNE and Diablo */
     HWND hwnd = g_ddraw->bnet_active ? FindWindowEx(HWND_DESKTOP, NULL, "SDlgDialog", NULL) : NULL;