diff --git a/Cargo.toml b/Cargo.toml
index 29707d7..aef686a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,7 +21,7 @@ parse = { path = "components/parse" }
 redis = { version = "0.15.1"}
 rand  = { version = "0.7" }
 tokio = { version = "0.2.18", features = ["full"] }
-tokio-util = { version = "0.2.0", features = ["full"] }
+tokio-util = { version = "0.6.6", features = ["full"] }
 tonic = "0.2"
 clap  = { version = "~2.33.0" } # command line argument parse
 epaxos = { path = "components/epaxos" }