diff --git a/needlehaystack/evaluators/openai.py b/needlehaystack/evaluators/openai.py
index 91baa955..a08cbe68 100644
--- a/needlehaystack/evaluators/openai.py
+++ b/needlehaystack/evaluators/openai.py
@@ -39,10 +39,15 @@ def __init__(self,
         if (not api_key):
             raise ValueError("NIAH_EVALUATOR_API_KEY must be in env for using openai evaluator.")
 
-        self.api_key = api_key
+        api_base = os.getenv("NIAH_MODEL_API_BASE")
+        if api_base is None:
+            api_base = f"https://api.openai.com/v1"
         
+        self.api_key = api_key
+        self.api_base = api_base 
         self.evaluator = ChatOpenAI(model=self.model_name,
                                     openai_api_key=self.api_key,
+                                    openai_api_base=self.api_base,
                                     **self.model_kwargs)
 
     def evaluate_response(self, response: str) -> int:
diff --git a/needlehaystack/providers/openai.py b/needlehaystack/providers/openai.py
index 1bc841e4..cd1052a4 100644
--- a/needlehaystack/providers/openai.py
+++ b/needlehaystack/providers/openai.py
@@ -41,10 +41,15 @@ def __init__(self,
         if (not api_key):
             raise ValueError("NIAH_MODEL_API_KEY must be in env.")
 
+        api_base = os.getenv("NIAH_MODEL_API_BASE")
+        if api_base is None:
+            api_base = f"https://api.openai.com/v1"
+    
         self.model_name = model_name
         self.model_kwargs = model_kwargs
         self.api_key = api_key
-        self.model = AsyncOpenAI(api_key=self.api_key)
+        self.api_base = api_base
+        self.model = AsyncOpenAI(api_key=self.api_key, base_url=self.api_base)
         self.tokenizer = tiktoken.encoding_for_model(self.model_name)
     
     async def evaluate_model(self, prompt: str) -> str: