diff --git a/sentinel.go b/sentinel.go
index 7963a0699..008f23cfe 100644
--- a/sentinel.go
+++ b/sentinel.go
@@ -201,8 +201,9 @@ func (opt *FailoverOptions) sentinelOptions(addr string) *Options {
 		MinRetryBackoff: opt.MinRetryBackoff,
 		MaxRetryBackoff: opt.MaxRetryBackoff,
 
-		ReadBufferSize:  opt.ReadBufferSize,
-		WriteBufferSize: opt.WriteBufferSize,
+		// The sentinel client uses a 4KiB read/write buffer size.
+		ReadBufferSize:  4096,
+		WriteBufferSize: 4096,
 
 		DialTimeout:           opt.DialTimeout,
 		ReadTimeout:           opt.ReadTimeout,