diff --git a/modules/buildbot/buildbot_nix.py b/modules/buildbot/buildbot_nix.py
index 9708503..af2d77a 100644
--- a/modules/buildbot/buildbot_nix.py
+++ b/modules/buildbot/buildbot_nix.py
@@ -118,7 +118,7 @@ class NixEvalCommand(buildstep.ShellMixin, steps.BuildStep):
             for line in self.observer.getStdout().split("\n"):
                 if line != "":
                     job = json.loads(line)
-                    if job["error"] is not None:
+                    if "error" in job.keys():
                         jobs.append(job)
             self.build.addStepsAfterCurrentStep(
                 [BuildTrigger(scheduler="nix-build", name="nix-build", jobs=jobs)]