diff --git a/include/ddk/ntddk.h b/include/ddk/ntddk.h
index 5c124ca944c..e76ccc9f8a8 100644
--- a/include/ddk/ntddk.h
+++ b/include/ddk/ntddk.h
@@ -214,6 +214,7 @@ NTSTATUS  WINAPI IoQueryDeviceDescription(PINTERFACE_TYPE,PULONG,PCONFIGURATION_
                                   PCONFIGURATION_TYPE,PULONG,PIO_QUERY_DEVICE_ROUTINE,PVOID);
 void      WINAPI IoRegisterDriverReinitialization(PDRIVER_OBJECT,PDRIVER_REINITIALIZE,PVOID);
 NTSTATUS  WINAPI IoRegisterShutdownNotification(PDEVICE_OBJECT);
+BOOLEAN   WINAPI MmIsAddressValid(void *);
 NTSTATUS  WINAPI PsSetLoadImageNotifyRoutine(PLOAD_IMAGE_NOTIFY_ROUTINE);
 void      WINAPI RtlInitializeGenericTableAvl(PRTL_AVL_TABLE,PRTL_AVL_COMPARE_ROUTINE,PRTL_AVL_ALLOCATE_ROUTINE, PRTL_AVL_FREE_ROUTINE,void *);
 void      WINAPI RtlInsertElementGenericTableAvl(PRTL_AVL_TABLE,void *,ULONG,BOOL*);