diff --git a/Cargo.lock b/Cargo.lock
index 4c80372..d4085f7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -100,12 +100,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "once_cell"
-version = "1.13.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "18a6dbe30758c9f83eb00cbea4ac95966305f5a7772f3f42ebfc7fc7eddbd8e1"
-
 [[package]]
 name = "parking_lot"
 version = "0.12.1"
@@ -224,9 +218,9 @@ dependencies = [
 
 [[package]]
 name = "tokio"
-version = "1.20.0"
+version = "1.20.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57aec3cfa4c296db7255446efb4928a6be304b431a806216105542a67b6ca82e"
+checksum = "eb78f30e4b41e98ca4cce5acb51168a033839a7af9e42b380355808e14e98ee0"
 dependencies = [
  "autocfg",
  "bytes",
@@ -234,7 +228,6 @@ dependencies = [
  "memchr",
  "mio",
  "num_cpus",
- "once_cell",
  "parking_lot",
  "pin-project-lite",
  "signal-hook-registry",
diff --git a/Cargo.toml b/Cargo.toml
index 518da4e..e5b6420 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,4 +7,4 @@ edition = "2021"
 
 [dependencies]
 rmodbus = "0.6.1"
-tokio = { version = "1.8.4", features = ["full", "time"] }
+tokio = { version = "1.20.4", features = ["full", "time"] }