diff --git a/channels_redis/core.py b/channels_redis/core.py
index 7c04ecd..47b4db2 100644
--- a/channels_redis/core.py
+++ b/channels_redis/core.py
@@ -11,7 +11,6 @@
 
 import msgpack
 from redis import asyncio as aioredis
-
 from channels.exceptions import ChannelFull
 from channels.layers import BaseChannelLayer
 
@@ -132,6 +131,8 @@ def create_pool(self, index):
         if "address" in host:
             return aioredis.ConnectionPool.from_url(host["address"])
         elif "master_name" in host:
+            # copy host dict to prevent original one from being modified
+            host= host.copy()
             sentinels = host.pop("sentinels")
             master_name = host.pop("master_name")
             sentinel_kwargs = host.pop("sentinel_kwargs", None)