diff --git a/src/flexmeasures_client/client.py b/src/flexmeasures_client/client.py
index 2decd025..1c8fe259 100644
--- a/src/flexmeasures_client/client.py
+++ b/src/flexmeasures_client/client.py
@@ -1196,6 +1196,7 @@ async def update_asset(self, asset_id: int, updates: dict) -> dict:
         This function raises a ValueError when an unhandled status code is returned.
         """
         uri = f"assets/{asset_id}"
+        updates = updates.copy()
         if "attributes" in updates:
             updates["attributes"] = json.dumps(updates["attributes"])
         if "flex_context" in updates:
@@ -1268,6 +1269,7 @@ async def update_sensor(self, sensor_id: int, updates: dict) -> dict:
         This function raises a ValueError when an unhandled status code is returned.
         """
         uri = f"sensors/{sensor_id}"
+        updates = updates.copy()
         if "attributes" in updates:
             updates["attributes"] = json.dumps(updates["attributes"])
         updated_sensor, status = await self.request(