Index: lib/rtl/workitem.c
===================================================================
--- lib/rtl/workitem.c	(revision 70072)
+++ lib/rtl/workitem.c	(working copy)
@@ -904,16 +904,38 @@
 }
 
 /*
- * @unimplemented
- */
+* @implemented
+*/
 NTSTATUS
 NTAPI
 RtlSetIoCompletionCallback(IN HANDLE FileHandle,
-                           IN PIO_APC_ROUTINE Callback,
-                           IN ULONG Flags)
+	IN PIO_APC_ROUTINE Callback,
+	IN ULONG Flags)
 {
-    UNIMPLEMENTED;
-    return STATUS_NOT_IMPLEMENTED;
+	IO_STATUS_BLOCK IoStatusBlock;
+	FILE_COMPLETION_INFORMATION FileCompletionInfo;
+	NTSTATUS Status;
+
+	DPRINT("RtlSetIoCompletionCallback(0x%p, 0x%p, 0x%x)\n", FileHandle, Callback, Flags);
+
+	/* Initialize the thread pool if not already initialized */
+	if (!IsThreadPoolInitialized())
+	{
+		Status = RtlpInitializeThreadPool();
+		if (!NT_SUCCESS(Status))
+			return Status;
+	}
+
+	FileCompletionInfo.Port = ThreadPoolCompletionPort;
+	FileCompletionInfo.Key = (PVOID)Callback;
+
+	Status = NtSetInformationFile(FileHandle,
+		                          &IoStatusBlock,
+		                          &FileCompletionInfo,
+		                          sizeof(FileCompletionInfo),
+		                          FileCompletionInformation);
+
+	return Status;
 }
 
 /*