diff --git a/src/judas_protocol/message.py b/src/judas_protocol/message.py
index cb16da6..dc221e5 100644
--- a/src/judas_protocol/message.py
+++ b/src/judas_protocol/message.py
@@ -117,14 +117,19 @@ class Message:
         return cls.from_json(data.decode("utf-8"))
 
     @classmethod
-    def ack(cls) -> Message:
+    def ack(cls, target_id: str) -> Message:
         """Create an ACK message.
 
+        Args:
+            target_id (str): The ID of the message to acknowledge.
+
         Returns:
             Message: The created ACK message.
         """
         return cls(
-            category=Category.CONTROL, action=ControlAction.ACK, payload={}
+            category=Category.CONTROL,
+            action=ControlAction.ACK,
+            payload={"target_id": target_id},
         )
 
     @classmethod