diff --git a/.github/workflows/cargo-test.yml b/.github/workflows/cargo-test.yml
index c17ab82314..4bceb086fd 100644
--- a/.github/workflows/cargo-test.yml
+++ b/.github/workflows/cargo-test.yml
@@ -12,7 +12,7 @@ jobs:
           fetch-depth: 1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly-2019-11-06
+          toolchain: nightly-2019-12-19
           components: clippy
           profile: minimal
           override: true
@@ -28,7 +28,7 @@ jobs:
           fetch-depth: 1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: nightly-2019-11-06
+          toolchain: nightly-2019-12-19
           components: rustfmt
           profile: minimal
           override: true
diff --git a/README.md b/README.md
index 54b4895f38..412fbd062d 100644
--- a/README.md
+++ b/README.md
@@ -132,35 +132,35 @@ You can create a block by sending a transaction through [JSON-RPC](https://githu
 ## Formatting
 
 
-Make sure you run `rustfmt` before creating a PR to the repo. You need to install the nightly-2019-11-06 version of `rustfmt`.
+Make sure you run `rustfmt` before creating a PR to the repo. You need to install the nightly-2019-12-19 version of `rustfmt`.
 
 ```sh
-rustup toolchain install nightly-2019-11-06
-rustup component add rustfmt --toolchain nightly-2019-11-06
+rustup toolchain install nightly-2019-12-19
+rustup component add rustfmt --toolchain nightly-2019-12-19
 ```
 
 To run `rustfmt`,
 
 ```sh
-cargo +nightly-2019-11-06 fmt
+cargo +nightly-2019-12-19 fmt
 ```
 
 ## Linting
 
 You should run `clippy` also. This is a lint tool for rust. It suggests more efficient/readable code.
 You can see [the clippy document](https://rust-lang.github.io/rust-clippy/master/index.html) for more information.
-You need to install the nightly-2019-11-06 version of `clippy`.
+You need to install the nightly-2019-12-19 version of `clippy`.
 
 ### Install
 ```sh
-rustup toolchain install nightly-2019-11-06
-rustup component add clippy --toolchain nightly-2019-11-06
+rustup toolchain install nightly-2019-12-19
+rustup component add clippy --toolchain nightly-2019-12-19
 ```
 
 ### Run
 
 ```sh
-cargo +nightly-2019-11-06 clippy --all --all-targets
+cargo +nightly-2019-12-19 clippy --all --all-targets
 ```
 
 ## Testing
diff --git a/util/io/src/lib.rs b/util/io/src/lib.rs
index 8f620b3b33..83584f1f50 100644
--- a/util/io/src/lib.rs
+++ b/util/io/src/lib.rs
@@ -27,33 +27,33 @@
 //! struct MyHandler;
 //!
 //! struct MyMessage {
-//! 	data: u32
+//!    data: u32
 //! }
 //!
 //! impl IoHandler<MyMessage> for MyHandler {
-//! 	fn initialize(&self, io: &IoContext<MyMessage>) -> IoHandlerResult<()> {
-//!			io.register_timer(0, Duration::from_secs(1));
-//!			Ok(())
-//!		}
+//!    fn initialize(&self, io: &IoContext<MyMessage>) -> IoHandlerResult<()> {
+//!        io.register_timer(0, Duration::from_secs(1));
+//!        Ok(())
+//!    }
 //!
-//!		fn timeout(&self, _io: &IoContext<MyMessage>, timer: TimerToken) -> IoHandlerResult<()> {
-//!			println!("Timeout {}", timer);
-//!			Ok(())
-//!		}
+//!    fn timeout(&self, _io: &IoContext<MyMessage>, timer: TimerToken) -> IoHandlerResult<()> {
+//!        println!("Timeout {}", timer);
+//!        Ok(())
+//!    }
 //!
-//!		fn message(&self, _io: &IoContext<MyMessage>, message: MyMessage) -> IoHandlerResult<()> {
-//!			println!("Message {}", message.data);
-//!			Ok(())
-//!		}
+//!    fn message(&self, _io: &IoContext<MyMessage>, message: MyMessage) -> IoHandlerResult<()> {
+//!        println!("Message {}", message.data);
+//!        Ok(())
+//!    }
 //! }
 //!
-//! fn main () {
-//! 	let mut service = IoService::<MyMessage>::start("Test").expect("Error creating network service");
-//! 	service.register_handler(Arc::new(MyHandler)).unwrap();
+//!  fn main () {
+//!    let mut service = IoService::<MyMessage>::start("Test").expect("Error creating network service");
+//!    service.register_handler(Arc::new(MyHandler)).unwrap();
 //!
-//! 	// Wait for quit condition
-//! 	// ...
-//! 	// Drop the service
+//!    // Wait for quit condition
+//!    // ...
+//!    // Drop the service
 //! }
 //! ```