diff --git a/litellm/types/utils.py b/litellm/types/utils.py
index 1d61e059fe2..54cc158ef2d 100644
--- a/litellm/types/utils.py
+++ b/litellm/types/utils.py
@@ -915,7 +915,7 @@ class Usage(CompletionUsage):
 
     server_tool_use: Optional[ServerToolUse] = None
 
-    prompt_tokens_details: Optional[Union[PromptTokensDetailsWrapper, PromptTokensDetails]] = None
+    prompt_tokens_details: Optional[PromptTokensDetailsWrapper] = None
     """Breakdown of tokens used in the prompt."""
 
     def __init__(
@@ -924,7 +924,7 @@ class Usage(CompletionUsage):
         completion_tokens: Optional[int] = None,
         total_tokens: Optional[int] = None,
         reasoning_tokens: Optional[int] = None,
-        prompt_tokens_details: Optional[Union[PromptTokensDetailsWrapper, PromptTokensDetails]] = None,
+        prompt_tokens_details: Optional[Union[PromptTokensDetailsWrapper, dict]] = None,
         completion_tokens_details: Optional[
             Union[CompletionTokensDetailsWrapper, dict]
         ] = None,
@@ -951,7 +951,7 @@ class Usage(CompletionUsage):
                 _completion_tokens_details = completion_tokens_details
 
         # handle prompt_tokens_details
-        _prompt_tokens_details: Optional[Union[PromptTokensDetailsWrapper, PromptTokensDetails]] = None
+        _prompt_tokens_details: Optional[PromptTokensDetailsWrapper] = None
 
         if prompt_tokens_details:
             if isinstance(prompt_tokens_details, dict):