diff --git a/optillm/__init__.py b/optillm/__init__.py
index 2ba7e5b..c21e426 100644
--- a/optillm/__init__.py
+++ b/optillm/__init__.py
@@ -1,5 +1,5 @@
 # Version information
-__version__ = "0.3.6"
+__version__ = "0.3.7"
 
 # Import from server module
 from .server import (
diff --git a/optillm/server.py b/optillm/server.py
index 17b1579..e5975df 100644
--- a/optillm/server.py
+++ b/optillm/server.py
@@ -714,9 +714,12 @@ def proxy():
     request_config.update({
         "stream": stream,
         "n": n,
-        "response_format": response_format,  # Add response_format to config
     })
 
+    # Only add response_format if it's not None
+    if response_format is not None:
+        request_config['response_format'] = response_format
+
     # Add token limits to request_config with proper priority
     if max_completion_tokens is not None:
         request_config['max_completion_tokens'] = max_completion_tokens
diff --git a/pyproject.toml b/pyproject.toml
index 6a909e6..7e8ded1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "optillm"
-version = "0.3.6"
+version = "0.3.7"
 description = "An optimizing inference proxy for LLMs."
 readme = "README.md"
 license = "Apache-2.0"