diff --git a/nixos/modules/misc/ids.nix b/nixos/modules/misc/ids.nix
index ac741caa953..efd8544d6a2 100644
--- a/nixos/modules/misc/ids.nix
+++ b/nixos/modules/misc/ids.nix
@@ -340,6 +340,7 @@
       cockroachdb = 313;
       zoneminder = 314;
       paperless = 315;
+      mailman = 316;
 
       # When adding a uid, make sure it doesn't match an existing gid. And don't use uids above 399!
 
@@ -640,6 +641,7 @@
       cockroachdb = 313;
       zoneminder = 314;
       paperless = 315;
+      mailman = 316;
 
       # When adding a gid, make sure it doesn't match an existing
       # uid. Users and groups with the same name should have equal