diff --git a/src/exo/worker/engines/mlx/generator/generate.py b/src/exo/worker/engines/mlx/generator/generate.py
index 2afe033e..c392f6a8 100644
--- a/src/exo/worker/engines/mlx/generator/generate.py
+++ b/src/exo/worker/engines/mlx/generator/generate.py
@@ -271,8 +271,12 @@ def mlx_generate(
                 prompt_tokens=int(out.prompt_tokens),
                 completion_tokens=completion_tokens,
                 total_tokens=int(out.prompt_tokens) + completion_tokens,
-                prompt_tokens_details=PromptTokensDetails(cached_tokens=prefix_hit_length),
-                completion_tokens_details=CompletionTokensDetails(reasoning_tokens=reasoning_tokens),
+                prompt_tokens_details=PromptTokensDetails(
+                    cached_tokens=prefix_hit_length
+                ),
+                completion_tokens_details=CompletionTokensDetails(
+                    reasoning_tokens=reasoning_tokens
+                ),
             )
 
         yield GenerationResponse(