diff --git a/dlls/amstream/amstream_private.h b/dlls/amstream/amstream_private.h
index bec107f819b..e71563cb115 100644
--- a/dlls/amstream/amstream_private.h
+++ b/dlls/amstream/amstream_private.h
@@ -37,9 +37,7 @@
 HRESULT multimedia_stream_create(IUnknown *outer, void **out) DECLSPEC_HIDDEN;
 HRESULT AMAudioData_create(IUnknown *pUnkOuter, LPVOID *ppObj) DECLSPEC_HIDDEN;
 HRESULT filter_create(IUnknown *outer, void **out) DECLSPEC_HIDDEN;
-HRESULT ddraw_stream_create(IMultiMediaStream *parent, const MSPID *purpose_id,
-        IUnknown *stream_object, STREAM_TYPE type, IAMMediaStream **stream) DECLSPEC_HIDDEN;
-HRESULT audio_stream_create(IMultiMediaStream *parent, const MSPID *purpose_id,
-        IUnknown *stream_object, STREAM_TYPE stream_type, IAMMediaStream **media_stream) DECLSPEC_HIDDEN;
+HRESULT ddraw_stream_create(IUnknown *outer, void **out) DECLSPEC_HIDDEN;
+HRESULT audio_stream_create(IUnknown *outer, void **out) DECLSPEC_HIDDEN;
 
 #endif /* __AMSTREAM_PRIVATE_INCLUDED__ */
diff --git a/dlls/amstream/audiostream.c b/dlls/amstream/audiostream.c
index a38cbc5f639..f9470fa5f90 100644
--- a/dlls/amstream/audiostream.c
+++ b/dlls/amstream/audiostream.c
@@ -1273,13 +1273,12 @@ static const IMemInputPinVtbl audio_meminput_vtbl =
     audio_meminput_ReceiveCanBlock,
 };
 
-HRESULT audio_stream_create(IMultiMediaStream *parent, const MSPID *purpose_id,
-        IUnknown *stream_object, STREAM_TYPE stream_type, IAMMediaStream **media_stream)
+HRESULT audio_stream_create(IUnknown *outer, void **out)
 {
     struct audio_stream *object;
-    HRESULT hr;
 
-    TRACE("(%p,%s,%p,%p)\n", parent, debugstr_guid(purpose_id), stream_object, media_stream);
+    if (outer)
+        return CLASS_E_NOAGGREGATION;
 
     object = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*object));
     if (!object)
@@ -1295,21 +1294,9 @@ HRESULT audio_stream_create(IMultiMediaStream *parent, const MSPID *purpose_id,
     list_init(&object->receive_queue);
     list_init(&object->update_queue);
 
-    hr = IAMMediaStream_Initialize(&object->IAMMediaStream_iface, stream_object, 0, purpose_id, stream_type);
-    if (FAILED(hr))
-    {
-        IAMMediaStream_Release(&object->IAMMediaStream_iface);
-        return hr;
-    }
+    TRACE("Created audio stream %p.\n", object);
 
-    hr = IAMMediaStream_JoinAMMultiMediaStream(&object->IAMMediaStream_iface, (IAMMultiMediaStream *)parent);
-    if (FAILED(hr))
-    {
-        IAMMediaStream_Release(&object->IAMMediaStream_iface);
-        return hr;
-    }
-
-    *media_stream = &object->IAMMediaStream_iface;
+    *out = &object->IAMMediaStream_iface;
 
     return S_OK;
 }
diff --git a/dlls/amstream/ddrawstream.c b/dlls/amstream/ddrawstream.c
index 8e99ea3bf55..1c924e40a20 100644
--- a/dlls/amstream/ddrawstream.c
+++ b/dlls/amstream/ddrawstream.c
@@ -926,13 +926,12 @@ static const IMemInputPinVtbl ddraw_meminput_vtbl =
     ddraw_meminput_ReceiveCanBlock,
 };
 
-HRESULT ddraw_stream_create(IMultiMediaStream *parent, const MSPID *purpose_id,
-        IUnknown *stream_object, STREAM_TYPE stream_type, IAMMediaStream **media_stream)
+HRESULT ddraw_stream_create(IUnknown *outer, void **out)
 {
     struct ddraw_stream *object;
-    HRESULT hr;
 
-    TRACE("(%p,%s,%p,%p)\n", parent, debugstr_guid(purpose_id), stream_object, media_stream);
+    if (outer)
+        return CLASS_E_NOAGGREGATION;
 
     object = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*object));
     if (!object)
@@ -946,21 +945,9 @@ HRESULT ddraw_stream_create(IMultiMediaStream *parent, const MSPID *purpose_id,
 
     InitializeCriticalSection(&object->cs);
 
-    hr = IAMMediaStream_Initialize(&object->IAMMediaStream_iface, stream_object, 0, purpose_id, stream_type);
-    if (FAILED(hr))
-    {
-        IAMMediaStream_Release(&object->IAMMediaStream_iface);
-        return hr;
-    }
+    TRACE("Created ddraw stream %p.\n", object);
 
-    hr = IAMMediaStream_JoinAMMultiMediaStream(&object->IAMMediaStream_iface, (IAMMultiMediaStream *)parent);
-    if (FAILED(hr))
-    {
-        IAMMediaStream_Release(&object->IAMMediaStream_iface);
-        return hr;
-    }
-
-    *media_stream = &object->IAMMediaStream_iface;
+    *out = &object->IAMMediaStream_iface;
 
     return S_OK;
 }
diff --git a/dlls/amstream/multimedia.c b/dlls/amstream/multimedia.c
index be8fd4ecbfc..e77392e483a 100644
--- a/dlls/amstream/multimedia.c
+++ b/dlls/amstream/multimedia.c
@@ -301,6 +301,7 @@ static HRESULT WINAPI multimedia_stream_GetFilter(IAMMultiMediaStream *iface,
 static void add_stream(struct multimedia_stream *mmstream, IAMMediaStream *stream, IMediaStream **ret_stream)
 {
     IMediaStreamFilter_AddMediaStream(mmstream->filter, stream);
+    IAMMediaStream_JoinAMMultiMediaStream(stream, &mmstream->IAMMultiMediaStream_iface);
     if (ret_stream)
     {
         *ret_stream = (IMediaStream *)stream;
@@ -377,19 +378,26 @@ static HRESULT WINAPI multimedia_stream_AddMediaStream(IAMMultiMediaStream *ifac
     }
 
     if (IsEqualGUID(PurposeId, &MSPID_PrimaryVideo))
-        hr = ddraw_stream_create((IMultiMediaStream*)iface, PurposeId, stream_object, This->type, &pStream);
+        hr = ddraw_stream_create(NULL, (void **)&pStream);
     else if (IsEqualGUID(PurposeId, &MSPID_PrimaryAudio))
-        hr = audio_stream_create((IMultiMediaStream*)iface, PurposeId, stream_object, This->type, &pStream);
+        hr = audio_stream_create(NULL, (void **)&pStream);
     else
         return MS_E_PURPOSEID;
 
-    if (SUCCEEDED(hr))
+    if (FAILED(hr))
+        return hr;
+
+    hr = IAMMediaStream_Initialize(pStream, stream_object, dwFlags, PurposeId, This->type);
+    if (FAILED(hr))
     {
-        add_stream(This, pStream, ret_stream);
         IAMMediaStream_Release(pStream);
+        return hr;
     }
 
-    return hr;
+    add_stream(This, pStream, ret_stream);
+    IAMMediaStream_Release(pStream);
+
+    return S_OK;
 }
 
 static HRESULT WINAPI multimedia_stream_OpenFile(IAMMultiMediaStream *iface,
diff --git a/dlls/amstream/tests/amstream.c b/dlls/amstream/tests/amstream.c
index 073e372c94f..13c00aac25a 100644
--- a/dlls/amstream/tests/amstream.c
+++ b/dlls/amstream/tests/amstream.c
@@ -730,7 +730,7 @@ static void test_add_stream(void)
     ok(hr == S_OK, "Got hr %#x.\n", hr);
     ok(stream == (IMediaStream *)&teststream, "Streams didn't match.\n");
     if (hr == S_OK) IMediaStream_Release(stream);
-    todo_wine ok(teststream.mmstream == mmstream, "IAMMultiMediaStream objects didn't match.\n");
+    ok(teststream.mmstream == mmstream, "IAMMultiMediaStream objects didn't match.\n");
     ok(teststream.filter == stream_filter, "IMediaStreamFilter objects didn't match.\n");
     todo_wine ok(!!teststream.graph, "Expected a non-NULL graph.\n");