diff --git a/dlls/wined3d/arb_program_shader.c b/dlls/wined3d/arb_program_shader.c
index 67eeef03720..becaa5fbe66 100644
--- a/dlls/wined3d/arb_program_shader.c
+++ b/dlls/wined3d/arb_program_shader.c
@@ -4744,8 +4744,8 @@ static const struct wine_rb_functions sig_tree_functions =
     sig_tree_compare
 };
 
-static HRESULT shader_arb_alloc(IWineD3DDevice *iface) {
-    IWineD3DDeviceImpl *This = (IWineD3DDeviceImpl *)iface;
+static HRESULT shader_arb_alloc(IWineD3DDeviceImpl *device)
+{
     struct shader_arb_priv *priv = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*priv));
     if(wine_rb_init(&priv->signature_tree, &sig_tree_functions) == -1)
     {
@@ -4753,7 +4753,7 @@ static HRESULT shader_arb_alloc(IWineD3DDevice *iface) {
         HeapFree(GetProcessHeap(), 0, priv);
         return E_OUTOFMEMORY;
     }
-    This->shader_priv = priv;
+    device->shader_priv = priv;
     return WINED3D_OK;
 }
 
diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index b6f6d2944a0..4efade0c74f 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -1963,7 +1963,7 @@ static HRESULT WINAPI IWineD3DDeviceImpl_Init3D(IWineD3DDevice *iface,
     if (This->depth_stencil)
         IWineD3DSurface_AddRef((IWineD3DSurface *)This->depth_stencil);
 
-    hr = This->shader_backend->shader_alloc_private(iface);
+    hr = This->shader_backend->shader_alloc_private(This);
     if(FAILED(hr)) {
         TRACE("Shader private data couldn't be allocated\n");
         goto err_out;
@@ -6244,7 +6244,7 @@ static HRESULT create_primary_opengl_context(IWineD3DDevice *iface, IWineD3DSwap
     create_dummy_textures(This);
     context_release(context);
 
-    hr = This->shader_backend->shader_alloc_private(iface);
+    hr = This->shader_backend->shader_alloc_private(This);
     if (FAILED(hr))
     {
         ERR("Failed to allocate shader private data, hr %#x.\n", hr);
diff --git a/dlls/wined3d/glsl_shader.c b/dlls/wined3d/glsl_shader.c
index 9f4940ef20e..2d19a34e2a9 100644
--- a/dlls/wined3d/glsl_shader.c
+++ b/dlls/wined3d/glsl_shader.c
@@ -4818,9 +4818,9 @@ static const struct wine_rb_functions wined3d_glsl_program_rb_functions =
     glsl_program_key_compare,
 };
 
-static HRESULT shader_glsl_alloc(IWineD3DDevice *iface) {
-    IWineD3DDeviceImpl *This = (IWineD3DDeviceImpl *)iface;
-    const struct wined3d_gl_info *gl_info = &This->adapter->gl_info;
+static HRESULT shader_glsl_alloc(IWineD3DDeviceImpl *device)
+{
+    const struct wined3d_gl_info *gl_info = &device->adapter->gl_info;
     struct shader_glsl_priv *priv = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(struct shader_glsl_priv));
     SIZE_T stack_size = wined3d_log2i(max(gl_info->limits.glsl_vs_float_constants,
             gl_info->limits.glsl_ps_float_constants)) + 1;
@@ -4858,7 +4858,7 @@ static HRESULT shader_glsl_alloc(IWineD3DDevice *iface) {
 
     priv->next_constant_version = 1;
 
-    This->shader_priv = priv;
+    device->shader_priv = priv;
     return WINED3D_OK;
 
 fail:
diff --git a/dlls/wined3d/shader.c b/dlls/wined3d/shader.c
index 1caa3b67be4..0af7667368d 100644
--- a/dlls/wined3d/shader.c
+++ b/dlls/wined3d/shader.c
@@ -1519,7 +1519,7 @@ static void shader_none_load_constants(const struct wined3d_context *context, ch
 static void shader_none_load_np2fixup_constants(void *shader_priv,
         const struct wined3d_gl_info *gl_info, const struct wined3d_state *state) {}
 static void shader_none_destroy(IWineD3DBaseShader *iface) {}
-static HRESULT shader_none_alloc(IWineD3DDevice *iface) {return WINED3D_OK;}
+static HRESULT shader_none_alloc(IWineD3DDeviceImpl *device) {return WINED3D_OK;}
 static void shader_none_free(IWineD3DDevice *iface) {}
 static BOOL shader_none_dirty_const(IWineD3DDevice *iface) {return FALSE;}
 
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index 566e67f48c3..42408322c59 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -759,7 +759,7 @@ typedef struct {
     void (*shader_load_np2fixup_constants)(void *shader_priv, const struct wined3d_gl_info *gl_info,
             const struct wined3d_state *state);
     void (*shader_destroy)(IWineD3DBaseShader *iface);
-    HRESULT (*shader_alloc_private)(IWineD3DDevice *iface);
+    HRESULT (*shader_alloc_private)(IWineD3DDeviceImpl *device);
     void (*shader_free_private)(IWineD3DDevice *iface);
     BOOL (*shader_dirtifyable_constants)(IWineD3DDevice *iface);
     void (*shader_get_caps)(const struct wined3d_gl_info *gl_info, struct shader_caps *caps);