diff --git a/easypost/util.py b/easypost/util.py
index b46555c..d3ee927 100644
--- a/easypost/util.py
+++ b/easypost/util.py
@@ -7,6 +7,7 @@
     Dict,
     List,
     Optional,
+    Union,
 )
 
 from easypost.constant import (
@@ -24,10 +25,11 @@
     InvalidParameterError,
     SignatureVerificationError,
 )
+from easypost.models.rate import Rate
 
 
 def get_lowest_object_rate(
-    easypost_object: EasyPostObject,
+    easypost_object: Union[EasyPostObject, Dict[str, Any]],
     carriers: Optional[List[str]] = None,
     services: Optional[List[str]] = None,
     rates_key: str = "rates",
@@ -53,7 +55,7 @@ def get_lowest_object_rate(
     return lowest_rate
 
 
-def get_lowest_smart_rate(smart_rates, delivery_days: int, delivery_accuracy: str):
+def get_lowest_smart_rate(smart_rates: List[Rate], delivery_days: int, delivery_accuracy: str):
     """Get the lowest SmartRate from a list of SmartRates."""
     valid_delivery_accuracy_values = {
         "percentile_50",