diff --git a/decision-task.py b/decision-task.py
index dae912b1d67..ad64b82d665 100644
--- a/decision-task.py
+++ b/decision-task.py
@@ -5,7 +5,7 @@ import json
 import pprint
 import taskcluster
 
-event = json.loads(environ["GITHUB_EVENT"])
+event = json.loads(os.environ["GITHUB_EVENT"])
 print("GitHub event:")
 pprint.pprint(event)
 print("")