diff --git a/CHANGELOG.md b/CHANGELOG.md
index e2717ca2e1..b4b1fe9ee5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@
 * [ENHANCEMENT] Query Frontend: Log number of split queries in `query stats` log. #5703
 * [BUGFIX] Distributor: Do not use label with empty values for sharding #5717
 * [BUGFIX] Query Frontend: queries with negative offset should check whether it is cacheable or not. #5719
+* [BUGFIX] Redis Cache: pass `cache_size` config correctly. #5734
 
 
 ## 1.16.0 2023-11-20
diff --git a/pkg/storage/tsdb/redis_client_config.go b/pkg/storage/tsdb/redis_client_config.go
index 1331080430..4d38221bd7 100644
--- a/pkg/storage/tsdb/redis_client_config.go
+++ b/pkg/storage/tsdb/redis_client_config.go
@@ -2,10 +2,12 @@ package tsdb
 
 import (
 	"flag"
+
 	"time"
 
 	"github.com/pkg/errors"
 	"github.com/thanos-io/thanos/pkg/cacheutil"
+	"github.com/thanos-io/thanos/pkg/model"
 
 	"github.com/cortexproject/cortex/pkg/util/tls"
 )
@@ -97,5 +99,6 @@ func (cfg *RedisClientConfig) ToRedisClientConfig() cacheutil.RedisClientConfig
 			ServerName:         cfg.TLS.ServerName,
 			InsecureSkipVerify: cfg.TLS.InsecureSkipVerify,
 		},
+		CacheSize: model.Bytes(cfg.CacheSize),
 	}
 }