diff --git a/litellm/cost_calculator.py b/litellm/cost_calculator.py
index 9b4dd80265c..041b4873d87 100644
--- a/litellm/cost_calculator.py
+++ b/litellm/cost_calculator.py
@@ -2226,18 +2226,20 @@ class BaseTokenUsageProcessor:
                         CompletionTokensDetailsWrapper()
                     )
 
-                # Check what keys exist in the model's completion_tokens_details
-                # Access model_fields on the class, not the instance, to avoid Pydantic 2.11+ deprecation warnings
                 for attr in type(usage.completion_tokens_details).model_fields:
                     if not attr.startswith("_") and not callable(
                         getattr(usage.completion_tokens_details, attr)
                     ):
-                        current_val = getattr(
-                            combined.completion_tokens_details, attr, 0
+                        current_val = (
+                            getattr(combined.completion_tokens_details, attr, 0)
+                            or 0
                         )
-                        new_val = getattr(usage.completion_tokens_details, attr, 0)
-
-                        if new_val is not None and current_val is not None:
+                        new_val = (
+                            getattr(usage.completion_tokens_details, attr, 0) or 0
+                        )
+                        if new_val is not None and isinstance(
+                            new_val, (int, float)
+                        ):
                             setattr(
                                 combined.completion_tokens_details,
                                 attr,