diff --git a/plugins/builder/osbuild.py b/plugins/builder/osbuild.py
index 45736b9..801c4c8 100644
--- a/plugins/builder/osbuild.py
+++ b/plugins/builder/osbuild.py
@@ -187,7 +187,7 @@ def as_dict(self):
 
 
 class ComposeStatusError:
-    def __init__(self, error_id: int, reason: str, details: Optional[Dict]):
+    def __init__(self, error_id: int, reason: str, details: Optional[Dict]=None):
         self.error_id = error_id
         self.reason = reason
         self.details = details