diff --git a/src/pipecat/services/aws/sagemaker/bidi_client.py b/src/pipecat/services/aws/sagemaker/bidi_client.py
index 8d7bdeaa1..1165bb89b 100644
--- a/src/pipecat/services/aws/sagemaker/bidi_client.py
+++ b/src/pipecat/services/aws/sagemaker/bidi_client.py
@@ -63,8 +63,8 @@ class SageMakerBidiClient:
         self,
         endpoint_name: str,
         region: str,
-        model_invocation_path: str = "",
-        model_query_string: str = "",
+        model_invocation_path: str | None = "",
+        model_query_string: str | None = "",
     ):
         """Initialize the SageMaker BiDi client.
 
diff --git a/src/pipecat/services/nvidia/sagemaker/stt.py b/src/pipecat/services/nvidia/sagemaker/stt.py
index b9a946a20..33b6a574f 100644
--- a/src/pipecat/services/nvidia/sagemaker/stt.py
+++ b/src/pipecat/services/nvidia/sagemaker/stt.py
@@ -201,8 +201,8 @@ class NvidiaSageMakerWebsocketSTTService(STTService):
             self._client = SageMakerBidiClient(
                 endpoint_name=self._endpoint_name,
                 region=self._region,
-                model_query_string="",
-                model_invocation_path="",
+                model_query_string=None,
+                model_invocation_path=None,
             )
             await self._client.start_session()
             await self._send_session_config()
diff --git a/src/pipecat/services/nvidia/sagemaker/tts.py b/src/pipecat/services/nvidia/sagemaker/tts.py
index 84d5aad8f..ba994b134 100644
--- a/src/pipecat/services/nvidia/sagemaker/tts.py
+++ b/src/pipecat/services/nvidia/sagemaker/tts.py
@@ -352,8 +352,8 @@ class NvidiaSageMakerWebsocketTTSService(InterruptibleTTSService):
             self._client = SageMakerBidiClient(
                 endpoint_name=self._endpoint_name,
                 region=self._region,
-                model_query_string="",
-                model_invocation_path="",
+                model_query_string=None,
+                model_invocation_path=None,
             )
             await self._client.start_session()
             await self._send_session_config()