diff --git a/dlls/ntoskrnl.exe/ntoskrnl.c b/dlls/ntoskrnl.exe/ntoskrnl.c
index f0892141c26..3c8b207a4a3 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.c
+++ b/dlls/ntoskrnl.exe/ntoskrnl.c
@@ -2071,6 +2071,11 @@ void * WINAPI ExRegisterCallback(PCALLBACK_OBJECT callback_object,
     return (void *)0xdeadbeef;
 }
 
+void WINAPI ExUnregisterCallback(void *callback_registration)
+{
+    FIXME("callback_registration %p stub.\n", callback_registration);
+}
+
 /***********************************************************************
  *           ExFreePool   (NTOSKRNL.EXE.@)
  */
diff --git a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
index dcec2375dfa..c4426566940 100644
--- a/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
+++ b/dlls/ntoskrnl.exe/ntoskrnl.exe.spec
@@ -191,7 +191,7 @@
 @ stdcall ExSetTimerResolution(long long)
 @ stub ExSystemExceptionFilter
 @ stdcall ExSystemTimeToLocalTime(ptr ptr) RtlSystemTimeToLocalTime
-@ stub ExUnregisterCallback
+@ stdcall ExUnregisterCallback(ptr)
 @ stdcall ExUuidCreate(ptr)
 @ stub ExVerifySuite
 @ stub ExWindowStationObjectType
diff --git a/include/ddk/wdm.h b/include/ddk/wdm.h
index 282ea14b77d..0d98680cfa5 100644
--- a/include/ddk/wdm.h
+++ b/include/ddk/wdm.h
@@ -1632,6 +1632,7 @@ void *    WINAPI ExRegisterCallback(PCALLBACK_OBJECT,PCALLBACK_FUNCTION,void*);
 void    FASTCALL ExReleaseFastMutexUnsafe(PFAST_MUTEX);
 void      WINAPI ExReleaseResourceForThreadLite(ERESOURCE*,ERESOURCE_THREAD);
 ULONG     WINAPI ExSetTimerResolution(ULONG,BOOLEAN);
+void      WINAPI ExUnregisterCallback(void*);
 
 void      WINAPI IoAcquireCancelSpinLock(KIRQL*);
 NTSTATUS  WINAPI IoAcquireRemoveLockEx(IO_REMOVE_LOCK*,void*,const char*,ULONG, ULONG);