diff --git a/src/sagemaker/sklearn/model.py b/src/sagemaker/sklearn/model.py
index d6d5e8422f..d953c1ffd9 100644
--- a/src/sagemaker/sklearn/model.py
+++ b/src/sagemaker/sklearn/model.py
@@ -307,7 +307,7 @@ def prepare_container_def(
         return sagemaker.container_def(deploy_image, model_data_uri, deploy_env)
 
     @validate_call_inputs
-    def serving_image_uri(self, region_name: str, instance_type: str, serverless_inference_config: Optional[ServerlessInferenceConfig] = None):
+    def serving_image_uri(self, region_name: str, instance_type: Optional[str] = None, serverless_inference_config: Optional[ServerlessInferenceConfig] = None):
         """Create a URI for the serving image.
 
         Args: