diff --git a/litellm/llms/anthropic.py b/litellm/llms/anthropic.py
index 4df032ba0097..f7d056bf9e57 100644
--- a/litellm/llms/anthropic.py
+++ b/litellm/llms/anthropic.py
@@ -105,8 +105,9 @@ def completion(
     optional_params=None,
     litellm_params=None,
     logger_fn=None,
+    headers={},
 ):
-    headers = validate_environment(api_key)
+    headers = { **validate_environment(api_key), **headers }
     if model in custom_prompt_dict:
         # check if the model has a registered custom prompt
         model_prompt_details = custom_prompt_dict[model]
diff --git a/litellm/main.py b/litellm/main.py
index e8022f464f55..1915eb7d0303 100644
--- a/litellm/main.py
+++ b/litellm/main.py
@@ -967,6 +967,7 @@ def completion(
                 encoding=encoding,  # for calculating input/output tokens
                 api_key=api_key,
                 logging_obj=logging,
+                headers=headers,
             )
             if "stream" in optional_params and optional_params["stream"] == True:
                 # don't try to access stream object,