diff --git a/dlls/d3d10/d3d10_main.c b/dlls/d3d10/d3d10_main.c
index 2c07bb3f5b5..f153ed37413 100644
--- a/dlls/d3d10/d3d10_main.c
+++ b/dlls/d3d10/d3d10_main.c
@@ -222,7 +222,7 @@ HRESULT WINAPI D3D10CreateEffectFromMemory(void *data, SIZE_T data_size, UINT fl
         return E_OUTOFMEMORY;
     }
 
-    object->vtbl = &d3d10_effect_vtbl;
+    object->ID3D10Effect_iface.lpVtbl = &d3d10_effect_vtbl;
     object->refcount = 1;
     ID3D10Device_AddRef(device);
     object->device = device;
@@ -231,11 +231,11 @@ HRESULT WINAPI D3D10CreateEffectFromMemory(void *data, SIZE_T data_size, UINT fl
     if (FAILED(hr))
     {
         ERR("Failed to parse effect\n");
-        IUnknown_Release((IUnknown *)object);
+        IUnknown_Release(&object->ID3D10Effect_iface);
         return hr;
     }
 
-    *effect = (ID3D10Effect *)object;
+    *effect = &object->ID3D10Effect_iface;
 
     TRACE("Created ID3D10Effect %p\n", object);
 
diff --git a/dlls/d3d10/d3d10_private.h b/dlls/d3d10/d3d10_private.h
index 7758dbef105..1df46114fc4 100644
--- a/dlls/d3d10/d3d10_private.h
+++ b/dlls/d3d10/d3d10_private.h
@@ -180,7 +180,7 @@ struct d3d10_effect_anonymous_shader
 extern const struct ID3D10EffectVtbl d3d10_effect_vtbl DECLSPEC_HIDDEN;
 struct d3d10_effect
 {
-    const struct ID3D10EffectVtbl *vtbl;
+    ID3D10Effect ID3D10Effect_iface;
     LONG refcount;
 
     ID3D10Device *device;
diff --git a/dlls/d3d10/effect.c b/dlls/d3d10/effect.c
index a258a99f5e8..542489cacf6 100644
--- a/dlls/d3d10/effect.c
+++ b/dlls/d3d10/effect.c
@@ -897,7 +897,7 @@ static HRESULT parse_fx10_object(struct d3d10_effect_object *o, const char **ptr
     enum d3d10_effect_object_operation operation;
     HRESULT hr;
     struct d3d10_effect *effect = o->pass->technique->effect;
-    ID3D10Effect *e = (ID3D10Effect *)effect;
+    ID3D10Effect *e = &effect->ID3D10Effect_iface;
 
     read_dword(ptr, &o->type);
     TRACE("Effect object is of type %#x.\n", o->type);
@@ -1885,6 +1885,11 @@ static void d3d10_effect_local_buffer_destroy(struct d3d10_effect_variable *l)
 
 /* IUnknown methods */
 
+static inline struct d3d10_effect *impl_from_ID3D10Effect(ID3D10Effect *iface)
+{
+    return CONTAINING_RECORD(iface, struct d3d10_effect, ID3D10Effect_iface);
+}
+
 static HRESULT STDMETHODCALLTYPE d3d10_effect_QueryInterface(ID3D10Effect *iface, REFIID riid, void **object)
 {
     TRACE("iface %p, riid %s, object %p\n", iface, debugstr_guid(riid), object);
@@ -1905,7 +1910,7 @@ static HRESULT STDMETHODCALLTYPE d3d10_effect_QueryInterface(ID3D10Effect *iface
 
 static ULONG STDMETHODCALLTYPE d3d10_effect_AddRef(ID3D10Effect *iface)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     ULONG refcount = InterlockedIncrement(&This->refcount);
 
     TRACE("%p increasing refcount to %u\n", This, refcount);
@@ -1915,7 +1920,7 @@ static ULONG STDMETHODCALLTYPE d3d10_effect_AddRef(ID3D10Effect *iface)
 
 static ULONG STDMETHODCALLTYPE d3d10_effect_Release(ID3D10Effect *iface)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     ULONG refcount = InterlockedDecrement(&This->refcount);
 
     TRACE("%p decreasing refcount to %u\n", This, refcount);
@@ -1990,7 +1995,7 @@ static BOOL STDMETHODCALLTYPE d3d10_effect_IsPool(ID3D10Effect *iface)
 
 static HRESULT STDMETHODCALLTYPE d3d10_effect_GetDevice(ID3D10Effect *iface, ID3D10Device **device)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
 
     TRACE("iface %p, device %p\n", iface, device);
 
@@ -2010,7 +2015,7 @@ static HRESULT STDMETHODCALLTYPE d3d10_effect_GetDesc(ID3D10Effect *iface, D3D10
 static struct ID3D10EffectConstantBuffer * STDMETHODCALLTYPE d3d10_effect_GetConstantBufferByIndex(ID3D10Effect *iface,
         UINT index)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     struct d3d10_effect_variable *l;
 
     TRACE("iface %p, index %u\n", iface, index);
@@ -2031,7 +2036,7 @@ static struct ID3D10EffectConstantBuffer * STDMETHODCALLTYPE d3d10_effect_GetCon
 static struct ID3D10EffectConstantBuffer * STDMETHODCALLTYPE d3d10_effect_GetConstantBufferByName(ID3D10Effect *iface,
         LPCSTR name)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     unsigned int i;
 
     TRACE("iface %p, name %s.\n", iface, debugstr_a(name));
@@ -2054,7 +2059,7 @@ static struct ID3D10EffectConstantBuffer * STDMETHODCALLTYPE d3d10_effect_GetCon
 
 static struct ID3D10EffectVariable * STDMETHODCALLTYPE d3d10_effect_GetVariableByIndex(ID3D10Effect *iface, UINT index)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     unsigned int i;
 
     TRACE("iface %p, index %u\n", iface, index);
@@ -2088,7 +2093,7 @@ static struct ID3D10EffectVariable * STDMETHODCALLTYPE d3d10_effect_GetVariableB
 
 static struct ID3D10EffectVariable * STDMETHODCALLTYPE d3d10_effect_GetVariableByName(ID3D10Effect *iface, LPCSTR name)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     unsigned int i;
 
     TRACE("iface %p, name %s.\n", iface, debugstr_a(name));
@@ -2135,7 +2140,7 @@ static struct ID3D10EffectVariable * STDMETHODCALLTYPE d3d10_effect_GetVariableB
 static struct ID3D10EffectVariable * STDMETHODCALLTYPE d3d10_effect_GetVariableBySemantic(ID3D10Effect *iface,
         LPCSTR semantic)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     unsigned int i;
 
     TRACE("iface %p, semantic %s\n", iface, debugstr_a(semantic));
@@ -2182,7 +2187,7 @@ static struct ID3D10EffectVariable * STDMETHODCALLTYPE d3d10_effect_GetVariableB
 static struct ID3D10EffectTechnique * STDMETHODCALLTYPE d3d10_effect_GetTechniqueByIndex(ID3D10Effect *iface,
         UINT index)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     struct d3d10_effect_technique *t;
 
     TRACE("iface %p, index %u\n", iface, index);
@@ -2203,7 +2208,7 @@ static struct ID3D10EffectTechnique * STDMETHODCALLTYPE d3d10_effect_GetTechniqu
 static struct ID3D10EffectTechnique * STDMETHODCALLTYPE d3d10_effect_GetTechniqueByName(ID3D10Effect *iface,
         LPCSTR name)
 {
-    struct d3d10_effect *This = (struct d3d10_effect *)iface;
+    struct d3d10_effect *This = impl_from_ID3D10Effect(iface);
     unsigned int i;
 
     TRACE("iface %p, name %s.\n", iface, debugstr_a(name));