diff --git a/lambda/sns_to_mqtt/__init__.py b/lambda/sns_to_mqtt/__init__.py
index b6d41c7..943f56a 100644
--- a/lambda/sns_to_mqtt/__init__.py
+++ b/lambda/sns_to_mqtt/__init__.py
@@ -75,7 +75,7 @@ def lambda_handler(event, context):
                 retain=False
             )
         client.publish(
-            topic=f'batch',
+            topic=os.getenv("MQTT_BATCH"),
             payload=json.dumps(payloads),
             qos=0,
             retain=False