diff --git a/dlls/d3d10core/d3d10core_private.h b/dlls/d3d10core/d3d10core_private.h
index 50d31b0bea3..17c3baed358 100644
--- a/dlls/d3d10core/d3d10core_private.h
+++ b/dlls/d3d10core/d3d10core_private.h
@@ -203,6 +203,7 @@ struct d3d10_pixel_shader
 
 HRESULT d3d10_pixel_shader_init(struct d3d10_pixel_shader *shader, struct d3d10_device *device,
         const void *byte_code, SIZE_T byte_code_length) DECLSPEC_HIDDEN;
+struct d3d10_pixel_shader *unsafe_impl_from_ID3D10PixelShader(ID3D10PixelShader *iface) DECLSPEC_HIDDEN;
 
 HRESULT shader_parse_signature(const char *data, DWORD data_size, struct wined3d_shader_signature *s) DECLSPEC_HIDDEN;
 void shader_free_signature(struct wined3d_shader_signature *s) DECLSPEC_HIDDEN;
diff --git a/dlls/d3d10core/device.c b/dlls/d3d10core/device.c
index 0f4b75fb402..149afa99a94 100644
--- a/dlls/d3d10core/device.c
+++ b/dlls/d3d10core/device.c
@@ -133,7 +133,7 @@ static void STDMETHODCALLTYPE d3d10_device_PSSetShader(ID3D10Device *iface,
         ID3D10PixelShader *shader)
 {
     struct d3d10_device *This = impl_from_ID3D10Device(iface);
-    struct d3d10_pixel_shader *ps = (struct d3d10_pixel_shader *)shader;
+    struct d3d10_pixel_shader *ps = unsafe_impl_from_ID3D10PixelShader(shader);
 
     TRACE("iface %p, shader %p\n", iface, shader);
 
diff --git a/dlls/d3d10core/shader.c b/dlls/d3d10core/shader.c
index fe112dcb3a2..79131e1cfdd 100644
--- a/dlls/d3d10core/shader.c
+++ b/dlls/d3d10core/shader.c
@@ -419,6 +419,11 @@ HRESULT d3d10_geometry_shader_init(struct d3d10_geometry_shader *shader, struct
     return S_OK;
 }
 
+static inline struct d3d10_pixel_shader *impl_from_ID3D10PixelShader(ID3D10PixelShader *iface)
+{
+    return CONTAINING_RECORD(iface, struct d3d10_pixel_shader, vtbl);
+}
+
 /* IUnknown methods */
 
 static HRESULT STDMETHODCALLTYPE d3d10_pixel_shader_QueryInterface(ID3D10PixelShader *iface,
@@ -553,3 +558,12 @@ HRESULT d3d10_pixel_shader_init(struct d3d10_pixel_shader *shader, struct d3d10_
 
     return S_OK;
 }
+
+struct d3d10_pixel_shader *unsafe_impl_from_ID3D10PixelShader(ID3D10PixelShader *iface)
+{
+    if (!iface)
+        return NULL;
+    assert(iface->lpVtbl == &d3d10_pixel_shader_vtbl);
+
+    return impl_from_ID3D10PixelShader(iface);
+}