diff --git a/modules/buildbot/buildbot_nix.py b/modules/buildbot/buildbot_nix.py
index b4b718d..37fb7fd 100644
--- a/modules/buildbot/buildbot_nix.py
+++ b/modules/buildbot/buildbot_nix.py
@@ -104,6 +104,7 @@ class NixEvalCommand(buildstep.ShellMixin, steps.BuildStep):
         super().__init__(**kwargs)
         self.observer = logobserver.BufferLogObserver()
         self.addLogObserver("Eval trace", self.observer)
+        self.logEnviron = False
 
     @defer.inlineCallbacks
     def run(self) -> Generator[Any, object, Any]: