diff --git a/deevirt_schema/api/stats.py b/deevirt_schema/api/stats.py
index a4d4edf..928ad58 100644
--- a/deevirt_schema/api/stats.py
+++ b/deevirt_schema/api/stats.py
@@ -14,6 +14,4 @@ class Stats(Stats):
     memory:Memory = Field()
     
 class MongoStats(Stats):
-    model_config = ConfigDict(arbitrary_types_allowed=True)
-    
-    created_at: time = Field(default_factory=time.time, alias='created_at')
\ No newline at end of file
+    created_at: Optional[float] = Field(default=None, alias='created_at')
\ No newline at end of file