diff --git a/dlls/qedit/main.c b/dlls/qedit/main.c
index 6b0375e78d5..40514d5a39b 100644
--- a/dlls/qedit/main.c
+++ b/dlls/qedit/main.c
@@ -42,12 +42,16 @@ BOOL WINAPI DllMain(HINSTANCE hInstDLL, DWORD fdwReason, LPVOID lpv)
  * DirectShow ClassFactory
  */
 typedef struct {
-    IClassFactory ITF_IClassFactory;
-
+    IClassFactory IClassFactory_iface;
     LONG ref;
     HRESULT (*pfnCreateInstance)(IUnknown *pUnkOuter, LPVOID *ppObj);
 } IClassFactoryImpl;
 
+static inline IClassFactoryImpl *impl_from_IClassFactory(IClassFactory *iface)
+{
+    return CONTAINING_RECORD(iface, IClassFactoryImpl, IClassFactory_iface);
+}
+
 struct object_creation_info
 {
     const CLSID *clsid;
@@ -60,34 +64,30 @@ static const struct object_creation_info object_creation[] =
     { &CLSID_SampleGrabber, SampleGrabber_create },
 };
 
-static HRESULT WINAPI
-DSCF_QueryInterface(LPCLASSFACTORY iface,REFIID riid,LPVOID *ppobj)
+static HRESULT WINAPI DSCF_QueryInterface(IClassFactory *iface, REFIID riid, void **ppobj)
 {
-    IClassFactoryImpl *This = (IClassFactoryImpl *)iface;
-
     if (IsEqualGUID(riid, &IID_IUnknown)
         || IsEqualGUID(riid, &IID_IClassFactory))
     {
         IClassFactory_AddRef(iface);
-        *ppobj = This;
+        *ppobj = iface;
         return S_OK;
     }
 
     *ppobj = NULL;
-    WARN("(%p)->(%s,%p),not found\n",This,debugstr_guid(riid),ppobj);
+    WARN("(%p)->(%s,%p), not found\n", iface, debugstr_guid(riid), ppobj);
     return E_NOINTERFACE;
 }
 
-static ULONG WINAPI DSCF_AddRef(LPCLASSFACTORY iface)
+static ULONG WINAPI DSCF_AddRef(IClassFactory *iface)
 {
-    IClassFactoryImpl *This = (IClassFactoryImpl *)iface;
+    IClassFactoryImpl *This = impl_from_IClassFactory(iface);
     return InterlockedIncrement(&This->ref);
 }
 
-static ULONG WINAPI DSCF_Release(LPCLASSFACTORY iface)
+static ULONG WINAPI DSCF_Release(IClassFactory *iface)
 {
-    IClassFactoryImpl *This = (IClassFactoryImpl *)iface;
-
+    IClassFactoryImpl *This = impl_from_IClassFactory(iface);
     ULONG ref = InterlockedDecrement(&This->ref);
 
     if (ref == 0)
@@ -96,9 +96,10 @@ static ULONG WINAPI DSCF_Release(LPCLASSFACTORY iface)
     return ref;
 }
 
-static HRESULT WINAPI DSCF_CreateInstance(LPCLASSFACTORY iface, LPUNKNOWN pOuter, REFIID riid, LPVOID *ppobj)
+static HRESULT WINAPI DSCF_CreateInstance(IClassFactory *iface, IUnknown *pOuter, REFIID riid,
+        void **ppobj)
 {
-    IClassFactoryImpl *This = (IClassFactoryImpl *)iface;
+    IClassFactoryImpl *This = impl_from_IClassFactory(iface);
     HRESULT hres;
     LPUNKNOWN punk;
 
@@ -116,9 +117,9 @@ static HRESULT WINAPI DSCF_CreateInstance(LPCLASSFACTORY iface, LPUNKNOWN pOuter
     return hres;
 }
 
-static HRESULT WINAPI DSCF_LockServer(LPCLASSFACTORY iface, BOOL dolock)
+static HRESULT WINAPI DSCF_LockServer(IClassFactory *iface, BOOL dolock)
 {
-    IClassFactoryImpl *This = (IClassFactoryImpl *)iface;
+    IClassFactoryImpl *This = impl_from_IClassFactory(iface);
     FIXME("(%p)->(%d),stub!\n",This,dolock);
     return S_OK;
 }
@@ -182,12 +183,12 @@ HRESULT WINAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID *ppv)
     factory = CoTaskMemAlloc(sizeof(*factory));
     if (factory == NULL) return E_OUTOFMEMORY;
 
-    factory->ITF_IClassFactory.lpVtbl = &DSCF_Vtbl;
+    factory->IClassFactory_iface.lpVtbl = &DSCF_Vtbl;
     factory->ref = 1;
 
     factory->pfnCreateInstance = object_creation[i].pfnCreateInstance;
 
-    *ppv = &(factory->ITF_IClassFactory);
+    *ppv = &factory->IClassFactory_iface;
     return S_OK;
 }