diff --git a/clients/python/lorax/types.py b/clients/python/lorax/types.py
index 0a834200b..e624a9e7b 100644
--- a/clients/python/lorax/types.py
+++ b/clients/python/lorax/types.py
@@ -279,7 +279,7 @@ class Details(BaseModel):
     # Decoder input tokens, empty if decoder_input_details is False
     prefill: List[InputToken]
     # Generated tokens
-    tokens: Optional[List[Token]]
+    tokens: List[Token]
     # Additional sequences when using the `best_of` parameter
     best_of_sequences: Optional[List[BestOfSequence]]
 
@@ -289,7 +289,7 @@ class Response(BaseModel):
     # Generated text
     generated_text: str
     # Generation details
-    details: Details
+    details: Optional[Details]
 
 
 # `generate_stream` details