diff --git a/aider/coder.py b/aider/coder.py
index 9fc78c3be..b105c4715 100755
--- a/aider/coder.py
+++ b/aider/coder.py
@@ -51,10 +51,10 @@ class Coder:
         verbose=False,
         openai_api_key=None,
     ):
-        if openai_api_key:
-            openai.api_key = openai_api_key
-        else:
+        if not openai_api_key:
             raise MissingAPIKeyError("No OpenAI API key provided.")
+        openai.api_key = openai_api_key
+        openai.api_base = args.openai_api_base
 
         self.verbose = verbose
         self.abs_fnames = set()
diff --git a/aider/main.py b/aider/main.py
index 3bba81d57..14ea79bb1 100644
--- a/aider/main.py
+++ b/aider/main.py
@@ -151,6 +151,12 @@ def main(args=None, input=None, output=None):
         help="Specify the OpenAI API key",
         env_var="OPENAI_API_KEY",
     )
+    parser.add_argument(
+        "--openai-api-base",
+        metavar="OPENAI_API_BASE",
+        default="https://api.openai.com/v1/chat/completions",
+        help="Specify the OpenAI API base endpoint (default: https://api.openai.com/v1/chat/completions)",
+    )
     parser.add_argument(
         "--dry-run",
         action="store_true",