diff --git a/pymodbus/server/simulator/http_server.py b/pymodbus/server/simulator/http_server.py
index 761687fc3..44e452fc5 100644
--- a/pymodbus/server/simulator/http_server.py
+++ b/pymodbus/server/simulator/http_server.py
@@ -157,6 +157,7 @@ def __init__(
         if "device_id" in server:
             # Designated ModBus unit address. Will only serve data if the address matches
             datastore = ModbusServerContext(slaves={int(server["device_id"]): self.datastore_context}, single=False)
+            del server["device_id"]
         else:
             # Will server any request regardless of addressing
             datastore = ModbusServerContext(slaves=self.datastore_context, single=True)