diff --git a/zipline_tardis_bundle/util.py b/zipline_tardis_bundle/util.py
index 63e4424..75b33c1 100644
--- a/zipline_tardis_bundle/util.py
+++ b/zipline_tardis_bundle/util.py
@@ -19,17 +19,12 @@
 
 import pandas as pd
 from tardis_dev import get_exchange_details
-from typing_extensions import override
 
 
-@dataclass
+@dataclass(frozen=True, eq=True)
 class Asset:
     symbol: str
 
-    @override
-    def __hash__(self) -> int:
-        return self.symbol.__hash__()
-
 
 @lru_cache
 def exchange_details_cached(exchange: str) -> Dict[Any, Any]: