diff --git a/reactos/dll/win32/advapi32/advapi32.spec b/reactos/dll/win32/advapi32/advapi32.spec
index ca87a083f65..39c090cd1d7 100644
--- a/reactos/dll/win32/advapi32/advapi32.spec
+++ b/reactos/dll/win32/advapi32/advapi32.spec
@@ -415,7 +415,7 @@
  @ stub MakeAbsoluteSD2
  @ stdcall MakeAbsoluteSD(ptr ptr ptr ptr ptr ptr ptr ptr ptr ptr ptr)
  @ stdcall MakeSelfRelativeSD(ptr ptr ptr)
- @ stub MapGenericMask #(ptr ptr)
+ @ stdcall MapGenericMask (ptr ptr) NTDLL.RtlMapGenericMask
  @ stdcall NotifyBootConfigStatus(long)
  @ stdcall NotifyChangeEventLog (long long)
  @ stdcall ObjectCloseAuditAlarmA(str ptr long)