diff --git a/src/together/resources/chat/completions.py b/src/together/resources/chat/completions.py
index 5e4b44b..f291e91 100644
--- a/src/together/resources/chat/completions.py
+++ b/src/together/resources/chat/completions.py
@@ -38,7 +38,7 @@ def create(
         echo: bool | None = None,
         n: int | None = None,
         safety_model: str | None = None,
-        response_format: Dict[str, str | Dict[str, Any]] | None = None,
+        response_format: Dict[str, Any] | None = None,
         tools: List[Dict[str, Any]] | None = None,
         tool_choice: str | Dict[str, str | Dict[str, str]] | None = None,
         **kwargs: Any,
diff --git a/src/together/types/chat_completions.py b/src/together/types/chat_completions.py
index 6e24215..8e5132f 100644
--- a/src/together/types/chat_completions.py
+++ b/src/together/types/chat_completions.py
@@ -28,6 +28,7 @@ class MessageRole(str, Enum):
 class ResponseFormatType(str, Enum):
     JSON_OBJECT = "json_object"
     JSON_SCHEMA = "json_schema"
+    REGEX = "regex"
 
 
 class FunctionCall(BaseModel):
@@ -71,9 +72,15 @@ class ChatCompletionMessage(BaseModel):
 class ResponseFormat(BaseModel):
     type: ResponseFormatType
     schema_: Dict[str, Any] | None = None
+    pattern: str | None = None
 
     def to_dict(self) -> Dict[str, Any]:
-        return {"schema": self.schema_, "type": self.type}
+        result: Dict[str, Any] = {"type": self.type.value}
+        if self.schema_ is not None:
+            result["schema"] = self.schema_
+        if self.pattern is not None:
+            result["pattern"] = self.pattern
+        return result
 
 
 class FunctionTool(BaseModel):