diff --git a/dlls/mscoree/metadata.c b/dlls/mscoree/metadata.c
index c9b8c723d92..7a5336d0447 100644
--- a/dlls/mscoree/metadata.c
+++ b/dlls/mscoree/metadata.c
@@ -41,10 +41,15 @@ WINE_DEFAULT_DEBUG_CHANNEL( mscoree );
 
 typedef struct MetaDataDispenser
 {
-    const struct IMetaDataDispenserExVtbl *lpVtbl;
+    IMetaDataDispenserEx IMetaDataDispenserEx_iface;
     LONG ref;
 } MetaDataDispenser;
 
+static inline MetaDataDispenser *impl_from_IMetaDataDispenserEx(IMetaDataDispenserEx *iface)
+{
+    return CONTAINING_RECORD(iface, MetaDataDispenser, IMetaDataDispenserEx_iface);
+}
+
 static HRESULT WINAPI MetaDataDispenser_QueryInterface(IMetaDataDispenserEx* iface,
     REFIID riid, void **ppvObject)
 {
@@ -69,7 +74,7 @@ static HRESULT WINAPI MetaDataDispenser_QueryInterface(IMetaDataDispenserEx* ifa
 
 static ULONG WINAPI MetaDataDispenser_AddRef(IMetaDataDispenserEx* iface)
 {
-    MetaDataDispenser *This = (MetaDataDispenser*)iface;
+    MetaDataDispenser *This = impl_from_IMetaDataDispenserEx(iface);
     ULONG ref = InterlockedIncrement(&This->ref);
 
     TRACE("%p ref=%u\n", This, ref);
@@ -81,7 +86,7 @@ static ULONG WINAPI MetaDataDispenser_AddRef(IMetaDataDispenserEx* iface)
 
 static ULONG WINAPI MetaDataDispenser_Release(IMetaDataDispenserEx* iface)
 {
-    MetaDataDispenser *This = (MetaDataDispenser*)iface;
+    MetaDataDispenser *This = impl_from_IMetaDataDispenserEx(iface);
     ULONG ref = InterlockedDecrement(&This->ref);
 
     TRACE("%p ref=%u\n", This, ref);
@@ -193,7 +198,7 @@ HRESULT MetaDataDispenser_CreateInstance(IUnknown **ppUnk)
     if (!This)
         return E_OUTOFMEMORY;
 
-    This->lpVtbl = &MetaDataDispenserVtbl;
+    This->IMetaDataDispenserEx_iface.lpVtbl = &MetaDataDispenserVtbl;
     This->ref = 1;
 
     *ppUnk = (IUnknown*)This;