diff --git a/dlls/mfplat/mfplat.spec b/dlls/mfplat/mfplat.spec
index f55a8237d35..8f5e7db6aee 100644
--- a/dlls/mfplat/mfplat.spec
+++ b/dlls/mfplat/mfplat.spec
@@ -25,7 +25,7 @@
 @ stub MFBeginGetHostByName
 @ stub MFBeginRegisterWorkQueueWithMMCSS
 @ stdcall MFBeginRegisterWorkQueueWithMMCSSEx(long wstr long long ptr ptr) rtworkq.RtwqBeginRegisterWorkQueueWithMMCSS
-@ stub MFBeginUnregisterWorkQueueWithMMCSS
+@ stdcall MFBeginUnregisterWorkQueueWithMMCSS(long ptr ptr) rtworkq.RtwqBeginUnregisterWorkQueueWithMMCSS
 @ stub MFBlockThread
 @ stub MFCalculateBitmapImageSize
 @ stdcall MFCalculateImageSize(ptr long long ptr)
@@ -87,8 +87,8 @@
 @ stub MFDeserializePresentationDescriptor
 @ stdcall MFEndCreateFile(ptr ptr)
 @ stub MFEndGetHostByName
-@ stub MFEndRegisterWorkQueueWithMMCSS
-@ stub MFEndUnregisterWorkQueueWithMMCSS
+@ stdcall MFEndRegisterWorkQueueWithMMCSS(ptr ptr) rtworkq.RtwqEndRegisterWorkQueueWithMMCSS
+@ stdcall MFEndUnregisterWorkQueueWithMMCSS(ptr) rtworkq.RtwqEndUnregisterWorkQueueWithMMCSS
 @ stub MFFrameRateToAverageTimePerFrame
 @ stub MFFreeAdaptersAddresses
 @ stub MFGetAdaptersAddresses
diff --git a/dlls/rtworkq/queue.c b/dlls/rtworkq/queue.c
index 07d124cfb73..f4e9f10d3f0 100644
--- a/dlls/rtworkq/queue.c
+++ b/dlls/rtworkq/queue.c
@@ -1533,6 +1533,27 @@ HRESULT WINAPI RtwqBeginRegisterWorkQueueWithMMCSS(DWORD queue, const WCHAR *cla
     return E_NOTIMPL;
 }
 
+HRESULT WINAPI RtwqEndRegisterWorkQueueWithMMCSS(IRtwqAsyncResult *result, DWORD *taskid)
+{
+    FIXME("%p, %p.\n", result, taskid);
+
+    return E_NOTIMPL;
+}
+
+HRESULT WINAPI RtwqBeginUnregisterWorkQueueWithMMCSS(DWORD queue, IRtwqAsyncCallback *callback, IUnknown *state)
+{
+    FIXME("%#x, %p, %p.\n", queue, callback, state);
+
+    return E_NOTIMPL;
+}
+
+HRESULT WINAPI RtwqEndUnregisterWorkQueueWithMMCSS(IRtwqAsyncResult *result)
+{
+    FIXME("%p.\n", result);
+
+    return E_NOTIMPL;
+}
+
 HRESULT WINAPI RtwqRegisterPlatformEvents(IRtwqPlatformEvents *events)
 {
     FIXME("%p.\n", events);
diff --git a/dlls/rtworkq/rtworkq.spec b/dlls/rtworkq/rtworkq.spec
index 09d877790d5..2200b0863bd 100644
--- a/dlls/rtworkq/rtworkq.spec
+++ b/dlls/rtworkq/rtworkq.spec
@@ -2,13 +2,13 @@
 @ stdcall RtwqAllocateSerialWorkQueue(long ptr)
 @ stdcall RtwqAllocateWorkQueue(long ptr)
 @ stdcall RtwqBeginRegisterWorkQueueWithMMCSS(long wstr long long ptr ptr)
-@ stub RtwqBeginUnregisterWorkQueueWithMMCSS
+@ stdcall RtwqBeginUnregisterWorkQueueWithMMCSS(long ptr ptr)
 @ stdcall RtwqCancelDeadline(long)
 @ stub RtwqCancelMultipleWaitingWorkItem
 @ stdcall RtwqCancelWorkItem(int64)
 @ stdcall RtwqCreateAsyncResult(ptr ptr ptr ptr)
-@ stub RtwqEndRegisterWorkQueueWithMMCSS
-@ stub RtwqEndUnregisterWorkQueueWithMMCSS
+@ stdcall RtwqEndRegisterWorkQueueWithMMCSS(ptr ptr)
+@ stdcall RtwqEndUnregisterWorkQueueWithMMCSS(ptr)
 @ stub RtwqGetPlatform
 @ stdcall RtwqGetWorkQueueMMCSSClass(long ptr ptr)
 @ stdcall RtwqGetWorkQueueMMCSSPriority(long ptr)
diff --git a/include/mfapi.h b/include/mfapi.h
index b1edeac02f6..e9b26f322c3 100644
--- a/include/mfapi.h
+++ b/include/mfapi.h
@@ -490,6 +490,7 @@ HRESULT WINAPI MFBeginCreateFile(MF_FILE_ACCESSMODE access_mode, MF_FILE_OPENMOD
         const WCHAR *path, IMFAsyncCallback *callback, IUnknown *state, IUnknown **cancel_cookie);
 HRESULT WINAPI MFBeginRegisterWorkQueueWithMMCSSEx(DWORD queue, const WCHAR *usage_class, DWORD taskid, LONG priority,
         IMFAsyncCallback *callback, IUnknown *state);
+HRESULT WINAPI MFBeginUnregisterWorkQueueWithMMCSS(DWORD queue, IMFAsyncCallback *callback, IUnknown *state);
 HRESULT WINAPI MFCalculateImageSize(REFGUID subtype, UINT32 width, UINT32 height, UINT32 *size);
 HRESULT WINAPI MFCancelCreateFile(IUnknown *cancel_cookie);
 HRESULT WINAPI MFCancelWorkItem(MFWORKITEM_KEY key);
@@ -517,6 +518,8 @@ HRESULT WINAPI MFCreateVideoMediaTypeFromSubtype(const GUID *subtype, IMFVideoMe
 HRESULT WINAPI MFCreateMemoryBuffer(DWORD max_length, IMFMediaBuffer **buffer);
 HRESULT WINAPI MFCreateWaveFormatExFromMFMediaType(IMFMediaType *type, WAVEFORMATEX **format, UINT32 *size, UINT32 flags);
 HRESULT WINAPI MFEndCreateFile(IMFAsyncResult *result, IMFByteStream **stream);
+HRESULT WINAPI MFEndRegisterWorkQueueWithMMCSS(IMFAsyncResult *result, DWORD *taskid);
+HRESULT WINAPI MFEndUnregisterWorkQueueWithMMCSS(IMFAsyncResult *result);
 void *  WINAPI MFHeapAlloc(SIZE_T size, ULONG flags, char *file, int line, EAllocationType type);
 void    WINAPI MFHeapFree(void *ptr);
 HRESULT WINAPI MFGetAttributesAsBlob(IMFAttributes *attributes, UINT8 *buffer, UINT size);
diff --git a/include/rtworkq.idl b/include/rtworkq.idl
index ed32df1c3bf..e7ff768074c 100644
--- a/include/rtworkq.idl
+++ b/include/rtworkq.idl
@@ -93,9 +93,11 @@ cpp_quote("HRESULT WINAPI RtwqAddPeriodicCallback(RTWQPERIODICCALLBACK callback,
 cpp_quote("HRESULT WINAPI RtwqAllocateSerialWorkQueue(DWORD target_queue, DWORD *queue);")
 cpp_quote("HRESULT WINAPI RtwqAllocateWorkQueue(RTWQ_WORKQUEUE_TYPE queue_type, DWORD *queue);")
 cpp_quote("HRESULT WINAPI RtwqBeginRegisterWorkQueueWithMMCSS(DWORD queue, const WCHAR *class, DWORD taskid, LONG priority, IRtwqAsyncCallback *callback, IUnknown *state);")
+cpp_quote("HRESULT WINAPI RtwqBeginUnregisterWorkQueueWithMMCSS(DWORD queue, IRtwqAsyncCallback *callback, IUnknown *state);")
 cpp_quote("HRESULT WINAPI RtwqCancelDeadline(HANDLE request);")
 cpp_quote("HRESULT WINAPI RtwqCancelWorkItem(RTWQWORKITEM_KEY key);")
 cpp_quote("HRESULT WINAPI RtwqCreateAsyncResult(IUnknown *object, IRtwqAsyncCallback *callback, IUnknown *state, IRtwqAsyncResult **result);")
+cpp_quote("HRESULT WINAPI RtwqEndRegisterWorkQueueWithMMCSS(IRtwqAsyncResult *result, DWORD *taskid);")
 cpp_quote("HRESULT WINAPI RtwqGetWorkQueueMMCSSClass(DWORD queue, WCHAR *class, DWORD *length);")
 cpp_quote("HRESULT WINAPI RtwqGetWorkQueueMMCSSPriority(DWORD queue, LONG *priority);")
 cpp_quote("HRESULT WINAPI RtwqGetWorkQueueMMCSSTaskId(DWORD queue, DWORD *taskid);")