diff --git a/dlls/ntdll/ntdll.spec b/dlls/ntdll/ntdll.spec
index 90f4747c25c..60fa7920b0c 100644
--- a/dlls/ntdll/ntdll.spec
+++ b/dlls/ntdll/ntdll.spec
@@ -277,7 +277,7 @@
 @ stub PfxRemovePrefix
 @ stub RestoreEm87Context
 @ stub RtlAbortRXact
-@ stub RtlAbsoluteToSelfRelativeSD
+@ stdcall RtlAbsoluteToSelfRelativeSD(ptr ptr ptr)
 @ stdcall RtlAcquirePebLock()
 @ stdcall RtlAcquireResourceExclusive(ptr long)
 @ stdcall RtlAcquireResourceShared(ptr long)
diff --git a/dlls/ntdll/sec.c b/dlls/ntdll/sec.c
index f247f3dd16b..f98636718f6 100644
--- a/dlls/ntdll/sec.c
+++ b/dlls/ntdll/sec.c
@@ -831,6 +831,21 @@ NTSTATUS WINAPI RtlSelfRelativeToAbsoluteSD(
     return status;
 }
 
+
+/**************************************************************************
+ *                 RtlAbsoluteToSelfRelativeSD [NTDLL.@]
+ */
+NTSTATUS WINAPI RtlAbsoluteToSelfRelativeSD(
+    PSECURITY_DESCRIPTOR AbsoluteSecurityDescriptor,
+    PSECURITY_DESCRIPTOR SelfRelativeSecurityDescriptor,
+    PULONG BufferLength)
+{
+    FIXME("%p %p %p\n", AbsoluteSecurityDescriptor,
+          SelfRelativeSecurityDescriptor, BufferLength);
+    return STATUS_NOT_IMPLEMENTED;
+}
+
+
 /*
  *	access control list's
  */