diff --git a/docs/markdown/Users.md b/docs/markdown/Users.md
index 37939dcf2..b2c161e9c 100644
--- a/docs/markdown/Users.md
+++ b/docs/markdown/Users.md
@@ -47,6 +47,7 @@ listed in the [`meson` GitHub topic](https://github.com/topics/meson).
  - [GtkDApp](https://gitlab.com/csoriano/GtkDApp), an application template for developing Flatpak apps with Gtk+ and D
  - [GVfs](https://git.gnome.org/browse/gvfs/), a userspace virtual filesystem designed to work with the I/O abstraction of GIO
  - [Hardcode-Tray](https://github.com/bil-elmoussaoui/Hardcode-Tray), fixes hardcoded tray icons in Linux
+ - [HelenOS](http://helenos.org), a portable microkernel-based multiserver operating system
  - [HexChat](https://github.com/hexchat/hexchat), a cross-platform IRC client in C
  - [IGT](https://cgit.freedesktop.org/xorg/app/intel-gpu-tools/), Linux kernel graphics driver test suite
  - [Irssi](https://github.com/irssi/irssi), a terminal chat client in C