diff --git a/lib/schema.ts b/lib/schema.ts
index 7078e718..759ccef1 100644
--- a/lib/schema.ts
+++ b/lib/schema.ts
@@ -727,7 +727,12 @@ const LiteLLMModel = z.object({
  */
 const LiteLLMConfig = z.object({
   environment_variables: z.map(z.string(), z.string()).optional(),
-  model_list: z.array(LiteLLMModel).optional().nullable().default([]),
+  model_list: z
+    .array(LiteLLMModel)
+    .optional()
+    .nullable()
+    .default([])
+    .transform((value) => value ?? []),
   litellm_settings: z.object({
     // ALL (https://github.com/BerriAI/litellm/blob/main/litellm/__init__.py)
     telemetry: z.boolean().default(false).optional(),
diff --git a/lib/serve/rest-api/src/utils/generate_litellm_config.py b/lib/serve/rest-api/src/utils/generate_litellm_config.py
index 81a1ba27..57cae97c 100644
--- a/lib/serve/rest-api/src/utils/generate_litellm_config.py
+++ b/lib/serve/rest-api/src/utils/generate_litellm_config.py
@@ -48,7 +48,9 @@ def generate_config(filepath: str) -> None:
         }
         for model in registered_models
     ]
-    config_contents["model_list"].extend(litellm_model_params)
+    config_models = config_contents["model_list"] or []  # ensure config_models is a list and not None
+    config_models.extend(litellm_model_params)
+    config_contents["model_list"] = config_models
     # Write updated config back to original path
     with open(filepath, "w") as fp:
         yaml.safe_dump(config_contents, fp)