diff --git a/krebs/3modules/buildbot/master.nix b/krebs/3modules/buildbot/master.nix
index e55bd95ea..c30f31e31 100644
--- a/krebs/3modules/buildbot/master.nix
+++ b/krebs/3modules/buildbot/master.nix
@@ -319,6 +319,7 @@ let
 
     users.extraUsers.buildbotMaster = {
       uid = genid "buildbotMaster";
+      group = "buildbotMaster";
       description = "Buildbot Master";
       home = cfg.workDir;
       createHome = false;
diff --git a/krebs/3modules/buildbot/slave.nix b/krebs/3modules/buildbot/slave.nix
index d877b9911..f97b50def 100644
--- a/krebs/3modules/buildbot/slave.nix
+++ b/krebs/3modules/buildbot/slave.nix
@@ -128,6 +128,7 @@ let
 
     users.extraUsers.buildbotSlave = {
       uid = genid "buildbotSlave";
+      group = "buildbotSlave";
       description = "Buildbot Slave";
       home = cfg.workDir;
       createHome = false;