diff --git a/dlls/amstream/ddrawstream.c b/dlls/amstream/ddrawstream.c
index 972c2b9f4d0..2526410cbff 100644
--- a/dlls/amstream/ddrawstream.c
+++ b/dlls/amstream/ddrawstream.c
@@ -70,7 +70,7 @@ struct ddraw_sample
     struct ddraw_stream *parent;
     IDirectDrawSurface *surface;
     RECT rect;
-    HANDLE update_event;
+    CONDITION_VARIABLE update_cv;
 
     struct list entry;
     HRESULT update_hr;
@@ -82,7 +82,7 @@ static HRESULT ddrawstreamsample_create(struct ddraw_stream *parent, IDirectDraw
 static void remove_queued_update(struct ddraw_sample *sample)
 {
     list_remove(&sample->entry);
-    SetEvent(sample->update_event);
+    WakeConditionVariable(&sample->update_cv);
 }
 
 static void flush_update_queue(struct ddraw_stream *stream, HRESULT update_hr)
@@ -1414,7 +1414,6 @@ static ULONG WINAPI ddraw_sample_Release(IDirectDrawStreamSample *iface)
 
         if (sample->surface)
             IDirectDrawSurface_Release(sample->surface);
-        CloseHandle(sample->update_event);
         HeapFree(GetProcessHeap(), 0, sample);
     }
 
@@ -1491,6 +1490,7 @@ static HRESULT WINAPI ddraw_sample_Update(IDirectDrawStreamSample *iface,
     }
     if (!sample->parent->peer || sample->parent->eos)
     {
+        sample->update_hr = MS_S_ENDOFSTREAM;
         LeaveCriticalSection(&sample->parent->cs);
         return MS_S_ENDOFSTREAM;
     }
@@ -1501,25 +1501,58 @@ static HRESULT WINAPI ddraw_sample_Update(IDirectDrawStreamSample *iface,
     }
 
     sample->update_hr = MS_S_PENDING;
-    ResetEvent(sample->update_event);
     list_add_tail(&sample->parent->update_queue, &sample->entry);
     WakeConditionVariable(&sample->parent->update_queued_cv);
 
-    LeaveCriticalSection(&sample->parent->cs);
-
     if (flags & SSUPDATE_ASYNC)
+    {
+        LeaveCriticalSection(&sample->parent->cs);
         return MS_S_PENDING;
+    }
 
-    WaitForSingleObject(sample->update_event, INFINITE);
+    while (sample->update_hr == MS_S_PENDING)
+        SleepConditionVariableCS(&sample->update_cv, &sample->parent->cs, INFINITE);
+
+    LeaveCriticalSection(&sample->parent->cs);
 
     return sample->update_hr;
 }
 
 static HRESULT WINAPI ddraw_sample_CompletionStatus(IDirectDrawStreamSample *iface, DWORD flags, DWORD milliseconds)
 {
-    FIXME("(%p)->(%x,%u): stub\n", iface, flags, milliseconds);
+    struct ddraw_sample *sample = impl_from_IDirectDrawStreamSample(iface);
+    HRESULT hr;
 
-    return E_NOTIMPL;
+    TRACE("sample %p, flags %#x, milliseconds %u.\n", sample, flags, milliseconds);
+
+    EnterCriticalSection(&sample->parent->cs);
+
+    if (sample->update_hr == MS_S_PENDING)
+    {
+        if (flags & (COMPSTAT_NOUPDATEOK | COMPSTAT_ABORT))
+        {
+            sample->update_hr = MS_S_NOUPDATE;
+            remove_queued_update(sample);
+        }
+        else if (flags & COMPSTAT_WAIT)
+        {
+            DWORD start_time = GetTickCount();
+            DWORD elapsed = 0;
+            while (sample->update_hr == MS_S_PENDING && elapsed < milliseconds)
+            {
+                DWORD sleep_time = milliseconds - elapsed;
+                if (!SleepConditionVariableCS(&sample->update_cv, &sample->parent->cs, sleep_time))
+                    break;
+                elapsed = GetTickCount() - start_time;
+            }
+        }
+    }
+
+    hr = sample->update_hr;
+
+    LeaveCriticalSection(&sample->parent->cs);
+
+    return hr;
 }
 
 /*** IDirectDrawStreamSample methods ***/
@@ -1583,7 +1616,7 @@ static HRESULT ddrawstreamsample_create(struct ddraw_stream *parent, IDirectDraw
     object->IDirectDrawStreamSample_iface.lpVtbl = &DirectDrawStreamSample_Vtbl;
     object->ref = 1;
     object->parent = parent;
-    object->update_event = CreateEventW(NULL, FALSE, FALSE, NULL);
+    InitializeConditionVariable(&object->update_cv);
     IAMMediaStream_AddRef(&parent->IAMMediaStream_iface);
     ++parent->sample_refs;
 
diff --git a/dlls/amstream/tests/amstream.c b/dlls/amstream/tests/amstream.c
index e5d1dd621f3..5467b519189 100644
--- a/dlls/amstream/tests/amstream.c
+++ b/dlls/amstream/tests/amstream.c
@@ -4028,6 +4028,21 @@ static DWORD CALLBACK ammediastream_receive(void *param)
     return 0;
 }
 
+static IStreamSample *streamsample_sample;
+static DWORD streamsample_flags;
+static DWORD streamsample_timeout;
+static HRESULT streamsample_expected_hr;
+
+static DWORD CALLBACK streamsample_completion_status(void *param)
+{
+    HRESULT hr;
+
+    hr = IStreamSample_CompletionStatus(streamsample_sample, streamsample_flags, streamsample_timeout);
+    ok(hr == streamsample_expected_hr, "Got hr %#x.\n", hr);
+
+    return 0;
+}
+
 static void test_audiostreamsample_update(void)
 {
     static const BYTE test_data[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
@@ -7221,6 +7236,282 @@ static void test_ddrawstreamsample_update(void)
     ok(!ref, "Got outstanding refcount %d.\n", ref);
 }
 
+static void test_ddrawstreamsample_completion_status(void)
+{
+    static const BYTE test_data[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
+    IAMMultiMediaStream *mmstream = create_ammultimediastream();
+    IDirectDrawStreamSample *stream_sample1;
+    IDirectDrawStreamSample *stream_sample2;
+    IDirectDrawMediaStream *ddraw_stream;
+    IMediaSample *media_sample;
+    IMediaFilter *media_filter;
+    struct testfilter source;
+    VIDEOINFO video_info;
+    IGraphBuilder *graph;
+    IMediaStream *stream;
+    AM_MEDIA_TYPE mt;
+    HANDLE thread;
+    HRESULT hr;
+    ULONG ref;
+    IPin *pin;
+
+    hr = IAMMultiMediaStream_Initialize(mmstream, STREAMTYPE_READ, 0, NULL);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IAMMultiMediaStream_AddMediaStream(mmstream, NULL, &MSPID_PrimaryVideo, 0, &stream);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IMediaStream_QueryInterface(stream, &IID_IDirectDrawMediaStream, (void **)&ddraw_stream);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IMediaStream_QueryInterface(stream, &IID_IPin, (void **)&pin);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IAMMultiMediaStream_GetFilterGraph(mmstream, &graph);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ok(graph != NULL, "Expected non-NULL graph.\n");
+    hr = IGraphBuilder_QueryInterface(graph, &IID_IMediaFilter, (void **)&media_filter);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    testfilter_init(&source);
+    hr = IGraphBuilder_AddFilter(graph, &source.filter.IBaseFilter_iface, NULL);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IMediaFilter_SetSyncSource(media_filter, NULL);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    video_info = rgb32_video_info;
+    video_info.bmiHeader.biWidth = 3;
+    video_info.bmiHeader.biHeight = 1;
+    mt = rgb32_mt;
+    mt.pbFormat = (BYTE *)&video_info;
+    hr = IGraphBuilder_ConnectDirect(graph, &source.source.pin.IPin_iface, pin, &mt);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_RUN);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawMediaStream_CreateSample(ddraw_stream, NULL, NULL, 0, &stream_sample1);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IDirectDrawMediaStream_CreateSample(ddraw_stream, NULL, NULL, 0, &stream_sample2);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, 100);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample2, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample2, 0, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    media_sample = ammediastream_allocate_sample(&source, test_data, sizeof(test_data));
+    hr = IMemInputPin_Receive(source.source.pMemInputPin, media_sample);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ref = IMediaSample_Release(media_sample);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample2, 0, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    media_sample = ammediastream_allocate_sample(&source, test_data, sizeof(test_data));
+    hr = IMemInputPin_Receive(source.source.pMemInputPin, media_sample);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ref = IMediaSample_Release(media_sample);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample2, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample2, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_NOUPDATEOK, 0);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    media_sample = ammediastream_allocate_sample(&source, test_data, sizeof(test_data));
+    hr = IMemInputPin_Receive(source.source.pMemInputPin, media_sample);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ref = IMediaSample_Release(media_sample);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample2, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample2, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_ABORT, 0);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    media_sample = ammediastream_allocate_sample(&source, test_data, sizeof(test_data));
+    hr = IMemInputPin_Receive(source.source.pMemInputPin, media_sample);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ref = IMediaSample_Release(media_sample);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample2, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_NOUPDATEOK | COMPSTAT_WAIT, INFINITE);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_ABORT | COMPSTAT_WAIT, INFINITE);
+    ok(hr == MS_S_NOUPDATE, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IPin_EndOfStream(pin);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == MS_S_ENDOFSTREAM, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == MS_S_ENDOFSTREAM, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_ENDOFSTREAM, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == MS_S_ENDOFSTREAM, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == MS_S_ENDOFSTREAM, "Got hr %#x.\n", hr);
+
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_STOP);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_RUN);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    streamsample_sample = (IStreamSample *)stream_sample1;
+    streamsample_flags = COMPSTAT_WAIT;
+    streamsample_timeout = INFINITE;
+    streamsample_expected_hr = S_OK;
+    thread = CreateThread(NULL, 0, streamsample_completion_status, NULL, 0, NULL);
+    ok(WaitForSingleObject(thread, 100) == WAIT_TIMEOUT, "CompletionStatus returned prematurely.\n");
+
+    media_sample = ammediastream_allocate_sample(&source, test_data, sizeof(test_data));
+    hr = IMemInputPin_Receive(source.source.pMemInputPin, media_sample);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ref = IMediaSample_Release(media_sample);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+
+    ok(!WaitForSingleObject(thread, 2000), "Wait timed out.\n");
+    CloseHandle(thread);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    streamsample_sample = (IStreamSample *)stream_sample1;
+    streamsample_flags = COMPSTAT_WAIT;
+    streamsample_timeout = INFINITE;
+    streamsample_expected_hr = MS_S_ENDOFSTREAM;
+    thread = CreateThread(NULL, 0, streamsample_completion_status, NULL, 0, NULL);
+    ok(WaitForSingleObject(thread, 100) == WAIT_TIMEOUT, "CompletionStatus returned prematurely.\n");
+
+    hr = IPin_EndOfStream(pin);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    ok(!WaitForSingleObject(thread, 2000), "Wait timed out.\n");
+    CloseHandle(thread);
+
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_STOP);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_RUN);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_STOP);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == MS_S_PENDING, "Got hr %#x.\n", hr);
+
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_RUN);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    media_sample = ammediastream_allocate_sample(&source, test_data, 6);
+    hr = IMemInputPin_Receive(source.source.pMemInputPin, media_sample);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+    ref = IMediaSample_Release(media_sample);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IAMMultiMediaStream_SetState(mmstream, STREAMSTATE_STOP);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_Update(stream_sample1, SSUPDATE_ASYNC, NULL, NULL, 0);
+    ok(hr == MS_E_NOTRUNNING, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, 0, 0);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    hr = IDirectDrawStreamSample_CompletionStatus(stream_sample1, COMPSTAT_WAIT, INFINITE);
+    ok(hr == S_OK, "Got hr %#x.\n", hr);
+
+    IGraphBuilder_Disconnect(graph, pin);
+    IGraphBuilder_Disconnect(graph, &source.source.pin.IPin_iface);
+
+    ref = IDirectDrawStreamSample_Release(stream_sample1);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+    ref = IDirectDrawStreamSample_Release(stream_sample2);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+    ref = IAMMultiMediaStream_Release(mmstream);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+    IMediaFilter_Release(media_filter);
+    ref = IGraphBuilder_Release(graph);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+    IPin_Release(pin);
+    IDirectDrawMediaStream_Release(ddraw_stream);
+    ref = IMediaStream_Release(stream);
+    ok(!ref, "Got outstanding refcount %d.\n", ref);
+}
+
 START_TEST(amstream)
 {
     const WCHAR *test_avi_path;
@@ -7276,6 +7567,7 @@ START_TEST(amstream)
 
     test_ddrawstreamsample_get_media_stream();
     test_ddrawstreamsample_update();
+    test_ddrawstreamsample_completion_status();
 
     test_ammediastream_join_am_multi_media_stream();
     test_ammediastream_join_filter();