diff --git a/tests/test_litellm/test_fireworks_serverless_model_costs.py b/tests/test_litellm/test_fireworks_serverless_model_costs.py
index b8d36b996df..e3404e477b7 100644
--- a/tests/test_litellm/test_fireworks_serverless_model_costs.py
+++ b/tests/test_litellm/test_fireworks_serverless_model_costs.py
@@ -14,6 +14,8 @@ import os
 
 import pytest
 
+from litellm import completion_cost
+from litellm.types.utils import Choices, Message, ModelResponse, Usage
 from litellm.utils import get_model_info
 
 
@@ -56,6 +58,20 @@ def test_bare_fireworks_ids_resolve_through_prefixed_entries():
         assert info["max_output_tokens"] == expected["max_output_tokens"]
 
 
+def test_deepseek_v4p1_flash_twin_costs():
+    for model in (
+        "fireworks_ai/deepseek-v4p1-flash",
+        "fireworks_ai/accounts/fireworks/models/deepseek-v4p1-flash",
+    ):
+        response = ModelResponse(
+            model=model,
+            choices=[Choices(index=0, message=Message(role="assistant", content="ok"))],
+            usage=Usage(prompt_tokens=1000, completion_tokens=1000, total_tokens=2000),
+        )
+        cost = completion_cost(completion_response=response, model=model)
+        assert cost == pytest.approx(8.8e-04)
+
+
 TWIN_PINNED_PRICES = {
     "deepseek-v4-flash-0731": {
         "input_cost_per_token": 2.2e-07,