diff --git a/dlls/ntdll/sec.c b/dlls/ntdll/sec.c
index 98afc4edd3d..8cadf7b5d60 100644
--- a/dlls/ntdll/sec.c
+++ b/dlls/ntdll/sec.c
@@ -303,7 +303,7 @@ NTSTATUS WINAPI RtlInitializeSid(
 	int i;
 	SID* pisid=pSid;
 
-	if (nSubAuthorityCount >= SID_MAX_SUB_AUTHORITIES)
+	if (nSubAuthorityCount > SID_MAX_SUB_AUTHORITIES)
 	  return STATUS_INVALID_PARAMETER;
 
 	pisid->Revision = SID_REVISION;
diff --git a/dlls/ntdll/tests/rtl.c b/dlls/ntdll/tests/rtl.c
index c075cae4ba2..269d26c8a16 100644
--- a/dlls/ntdll/tests/rtl.c
+++ b/dlls/ntdll/tests/rtl.c
@@ -3619,7 +3619,6 @@ static void test_RtlInitializeSid(void)
     ok(!status, "Unexpected status %#lx.\n", status);
 
     status = RtlInitializeSid(sid, &sid_ident, SID_MAX_SUB_AUTHORITIES);
-    todo_wine
     ok(!status, "Unexpected status %#lx.\n", status);
 
     status = RtlInitializeSid(sid, &sid_ident, SID_MAX_SUB_AUTHORITIES + 1);