Microsoft has quietly ignored its 31 December deadline for the end of free security updates for users of its NT4 operating system.
Microsoft this week made available two patches for "critical" security flaws in its Windows operating system, and NT4 was among the systems patched.
In a statement Microsoft said this was unlikely to occur again.
"Windows NT 4.0 Server Service Pack 6a and Windows NT 4.0 Server Terminal Server Edition Service Pack 6 reached the end of their life cycles on 31 December 2004," the company stated.
"In this case, the majority of the steps that are required to address this vulnerability were completed before this date. Therefore, we have decided to release a security update for this operating system version as part of this security bulletin."
Microsoft added, "We do not anticipate doing this for future vulnerabilities that may affect this operating system version, but we reserve the right to produce updates and to make these updates available when necessary."