diff --git a/postfix_mta_sts_resolver/redis_cache.py b/postfix_mta_sts_resolver/redis_cache.py
index 3e397bbb34d144485db332151481f739c882f144..4644cb379fdd928d0c9a35c7f2ea4ded299c1b21 100644
--- a/postfix_mta_sts_resolver/redis_cache.py
+++ b/postfix_mta_sts_resolver/redis_cache.py
@@ -104,7 +104,7 @@ class RedisSentinelCache(BaseCache):
         sentinel = aioredis.sentinel.Sentinel(self._opts['sentinels'])
         sentinel_master_name = self._opts['sentinel_master_name']
         for key in ['sentinels', 'sentinel_master_name']:
-          self._opts.pop(key)
+            self._opts.pop(key)
         opts = dict((k,v) for k, v in self._opts.items())
         self._pool = sentinel.master_for(sentinel_master_name, **opts)