diff --git a/rustfmt.toml b/rustfmt.toml
index 82fd485..0124e0d 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -2,6 +2,7 @@ use_small_heuristics = "Default"
 hard_tabs = false
 imports_layout = "HorizontalVertical"
 imports_granularity = "Crate"
+group_imports = "StdExternalCrate"
 match_block_trailing_comma = true
 max_width = 120
 newline_style = "Unix"
diff --git a/src/io/compat/futures.rs b/src/io/compat/futures.rs
index f772b0f..ddc3bee 100644
--- a/src/io/compat/futures.rs
+++ b/src/io/compat/futures.rs
@@ -1,12 +1,14 @@
-use super::Compat;
-use crate::io::AsyncSocket;
-use futures_io::{AsyncRead, AsyncWrite};
 use std::{
     io::Result as IoResult,
     pin::Pin,
     task::{Context, Poll},
 };
 
+use futures_io::{AsyncRead, AsyncWrite};
+
+use super::Compat;
+use crate::io::AsyncSocket;
+
 impl<S> AsyncSocket for Compat<S>
 where S: AsyncRead + AsyncWrite + Unpin
 {
diff --git a/src/io/mod.rs b/src/io/mod.rs
index 8672ad3..efd45f2 100644
--- a/src/io/mod.rs
+++ b/src/io/mod.rs
@@ -3,7 +3,6 @@
 #[cfg(feature = "tokio")]
 mod tokio;
 
-use futures_util::ready;
 use std::{
     future::Future,
     io::{Error, ErrorKind},
@@ -12,6 +11,8 @@ use std::{
     task::{Context, Poll},
 };
 
+use futures_util::ready;
+
 #[cfg(feature = "futures-io")]
 mod compat;
 #[cfg(feature = "futures-io")]
diff --git a/src/io/tokio.rs b/src/io/tokio.rs
index 4d290a4..ecfc4f2 100644
--- a/src/io/tokio.rs
+++ b/src/io/tokio.rs
@@ -1,14 +1,16 @@
 //! AsyncSocket trait implementation for tokio's AsyncRead + AsyncWrite
 //! traits.
-use super::AsyncSocket;
-use futures_util::ready;
 use std::{
     io::Result as IoResult,
     pin::Pin,
     task::{Context, Poll},
 };
+
+use futures_util::ready;
 use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
 
+use super::AsyncSocket;
+
 impl<S> AsyncSocket for S
 where S: AsyncRead + AsyncWrite
 {
diff --git a/src/lib.rs b/src/lib.rs
index 83b9ed5..c5e75d2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,8 +1,3 @@
-use either::Either;
-use futures_util::{
-    future,
-    stream::{self, Once, Stream},
-};
 use std::{
     borrow::Cow,
     io::Result as IoResult,
@@ -12,7 +7,12 @@ use std::{
     vec,
 };
 
+use either::Either;
 pub use error::Error;
+use futures_util::{
+    future,
+    stream::{self, Once, Stream},
+};
 
 pub type Result<T> = std::result::Result<T, Error>;
 
@@ -265,10 +265,11 @@ pub mod tcp;
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use futures_executor::block_on;
     use futures_util::StreamExt;
 
+    use super::*;
+
     fn to_proxy_addrs<T: ToProxyAddrs>(t: T) -> Result<Vec<SocketAddr>> {
         Ok(block_on(t.to_proxy_addrs().map(Result::unwrap).collect()))
     }
diff --git a/src/tcp/socks4.rs b/src/tcp/socks4.rs
index c6a74d8..2ea1bf9 100644
--- a/src/tcp/socks4.rs
+++ b/src/tcp/socks4.rs
@@ -1,12 +1,3 @@
-use crate::{
-    io::{AsyncSocket, AsyncSocketExt},
-    Error,
-    IntoTargetAddr,
-    Result,
-    TargetAddr,
-};
-
-use futures_util::stream::{self, Fuse, Stream, StreamExt};
 use std::{
     borrow::Borrow,
     io,
@@ -16,11 +7,20 @@ use std::{
     task::{Context, Poll},
 };
 
-#[cfg(feature = "tokio")]
-use crate::ToProxyAddrs;
+use futures_util::stream::{self, Fuse, Stream, StreamExt};
 #[cfg(feature = "tokio")]
 use tokio::net::TcpStream;
 
+#[cfg(feature = "tokio")]
+use crate::ToProxyAddrs;
+use crate::{
+    io::{AsyncSocket, AsyncSocketExt},
+    Error,
+    IntoTargetAddr,
+    Result,
+    TargetAddr,
+};
+
 #[repr(u8)]
 #[derive(Clone, Copy)]
 enum CommandV4 {
diff --git a/src/tcp/socks5.rs b/src/tcp/socks5.rs
index dc30027..28efcac 100644
--- a/src/tcp/socks5.rs
+++ b/src/tcp/socks5.rs
@@ -1,12 +1,3 @@
-use crate::{
-    io::{AsyncSocket, AsyncSocketExt},
-    Authentication,
-    Error,
-    IntoTargetAddr,
-    Result,
-    TargetAddr,
-};
-
 use std::{
     borrow::Borrow,
     io,
@@ -17,11 +8,19 @@ use std::{
 };
 
 use futures_util::stream::{self, Fuse, Stream, StreamExt};
+#[cfg(feature = "tokio")]
+use tokio::net::TcpStream;
 
 #[cfg(feature = "tokio")]
 use crate::ToProxyAddrs;
-#[cfg(feature = "tokio")]
-use tokio::net::TcpStream;
+use crate::{
+    io::{AsyncSocket, AsyncSocketExt},
+    Authentication,
+    Error,
+    IntoTargetAddr,
+    Result,
+    TargetAddr,
+};
 
 #[repr(u8)]
 #[derive(Clone, Copy)]
diff --git a/tests/common/futures_utils.rs b/tests/common/futures_utils.rs
index 06d866f..1f4a50a 100644
--- a/tests/common/futures_utils.rs
+++ b/tests/common/futures_utils.rs
@@ -1,13 +1,13 @@
-use super::*;
-use futures_util::{io::copy, AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
-use once_cell::sync::OnceCell;
-use smol::net::{unix::UnixStream, TcpListener};
 use std::{
     future::Future,
     io::{Read, Write},
     net::{SocketAddr, TcpStream as StdTcpStream},
     sync::Mutex,
 };
+
+use futures_util::{io::copy, AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
+use once_cell::sync::OnceCell;
+use smol::net::{unix::UnixStream, TcpListener};
 use tokio_socks::{
     io::Compat,
     tcp::{socks4::Socks4Listener, socks5::Socks5Listener},
@@ -15,6 +15,8 @@ use tokio_socks::{
     Result,
 };
 
+use super::*;
+
 pub async fn echo_server() -> Result<()> {
     let listener = TcpListener::bind(&SocketAddr::from(([0, 0, 0, 0], 10007))).await?;
     loop {
diff --git a/tests/common/tokio_utils.rs b/tests/common/tokio_utils.rs
index 7982dfc..aaf316b 100644
--- a/tests/common/tokio_utils.rs
+++ b/tests/common/tokio_utils.rs
@@ -1,10 +1,10 @@
-use super::*;
-use once_cell::sync::OnceCell;
 use std::{
     io::{Read, Write},
     net::{SocketAddr, TcpStream as StdTcpStream},
     sync::Mutex,
 };
+
+use once_cell::sync::OnceCell;
 use tokio::{
     io::{copy, split, AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt},
     net::{TcpListener, UnixStream},
@@ -16,6 +16,8 @@ use tokio_socks::{
     Result,
 };
 
+use super::*;
+
 pub async fn echo_server() -> Result<()> {
     let listener = TcpListener::bind(&SocketAddr::from(([0, 0, 0, 0], 10007))).await?;
     loop {