diff --git a/Cargo.toml b/Cargo.toml
index 1f48182..344150b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,6 +6,7 @@ license = "Apache-2.0"
 authors = ["The TiKV Project Authors"]
 repository = "https://github.com/tikv/client-rust"
 description = "The rust language implementation of TiKV client."
+edition = "2018"
 
 [lib]
 name = "tikv_client"
diff --git a/examples/raw.rs b/examples/raw.rs
index c8bfbdf..403c1e7 100644
--- a/examples/raw.rs
+++ b/examples/raw.rs
@@ -11,12 +11,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-extern crate futures;
-extern crate tikv_client;
-
-use std::path::PathBuf;
-
 use futures::future::Future;
+use std::path::PathBuf;
 use tikv_client::*;
 
 fn main() {
diff --git a/examples/transaction.rs b/examples/transaction.rs
index 3c77c07..23a1e28 100644
--- a/examples/transaction.rs
+++ b/examples/transaction.rs
@@ -11,15 +11,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-extern crate futures;
-extern crate tikv_client;
-
+use futures::{future, Future, Stream};
 use std::ops::RangeBounds;
 use std::path::PathBuf;
-
-use futures::{future, Future, Stream};
-use tikv_client::transaction::{Client, IsolationLevel};
-use tikv_client::*;
+use tikv_client::{
+    transaction::{Client, IsolationLevel},
+    Config, Key, KvPair, Value,
+};
 
 fn puts(client: &Client, pairs: impl IntoIterator<Item = impl Into<KvPair>>) {
     let mut txn = client.begin();
@@ -28,7 +26,8 @@ fn puts(client: &Client, pairs: impl IntoIterator<Item = impl Into<KvPair>>) {
             .into_iter()
             .map(Into::into)
             .map(|p| txn.set(p.key().clone(), p.value().clone())),
-    ).wait()
+    )
+    .wait()
     .expect("Could not set key value pairs");
     txn.commit().wait().expect("Could not commit transaction");
 }
@@ -49,10 +48,12 @@ fn scan(client: &Client, range: impl RangeBounds<Key>, mut limit: usize) {
                 limit -= 1;
                 true
             })
-        }).for_each(|pair| {
+        })
+        .for_each(|pair| {
             println!("{:?}", pair);
             Ok(())
-        }).wait()
+        })
+        .wait()
         .expect("Could not scan keys");
 }
 
@@ -63,7 +64,8 @@ fn dels(client: &Client, keys: impl IntoIterator<Item = Key>) {
         .into_iter()
         .map(|p| {
             txn.delete(p).wait().expect("Could not delete key");
-        }).collect();
+        })
+        .collect();
     txn.commit().wait().expect("Could not commit transaction");
 }
 
diff --git a/rust-toolchain b/rust-toolchain
new file mode 100644
index 0000000..870bbe4
--- /dev/null
+++ b/rust-toolchain
@@ -0,0 +1 @@
+stable
\ No newline at end of file
diff --git a/src/errors.rs b/src/errors.rs
index a8d8148..66a9a20 100644
--- a/src/errors.rs
+++ b/src/errors.rs
@@ -11,10 +11,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::error;
-use std::result;
+use grpcio;
+use quick_error::quick_error;
+use std::{error, result};
 
-quick_error!{
+quick_error! {
     #[derive(Debug)]
     pub enum Error {
         Io(err: ::std::io::Error) {
@@ -22,7 +23,7 @@ quick_error!{
             cause(err)
             description(err.description())
         }
-        Grpc(err: ::grpc::Error) {
+        Grpc(err: grpcio::Error) {
             from()
             cause(err)
             description(err.description())
diff --git a/src/lib.rs b/src/lib.rs
index 1827b26..3589dc8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -11,23 +11,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-extern crate futures;
-extern crate serde;
-#[macro_use]
-extern crate serde_derive;
-#[macro_use]
-extern crate quick_error;
-extern crate grpcio as grpc;
+use serde_derive::*;
+use std::ops::Deref;
+use std::path::PathBuf;
 
 pub mod errors;
 pub mod raw;
 pub mod transaction;
 
-use std::ops::Deref;
-use std::path::PathBuf;
-
-pub use errors::Error;
-pub use errors::Result;
+pub use crate::errors::Error;
+pub use crate::errors::Result;
 
 #[derive(Default, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
 pub struct Key(Vec<u8>);
diff --git a/src/raw.rs b/src/raw.rs
index 0bad042..5e97d17 100644
--- a/src/raw.rs
+++ b/src/raw.rs
@@ -11,11 +11,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::ops::RangeBounds;
-
+use crate::{Config, Error, Key, KvPair, Value};
 use futures::{Future, Poll};
-
-use {Config, Error, Key, KvPair, Value};
+use std::ops::RangeBounds;
 
 #[derive(Default, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
 pub struct ColumnFamily(String);
@@ -388,7 +386,7 @@ impl Future for Connect {
 pub struct Client;
 
 impl Client {
-    #![cfg_attr(feature = "cargo-clippy", allow(new_ret_no_self))]
+    #![allow(clippy::new_ret_no_self)]
     pub fn new(config: &Config) -> Connect {
         Connect::new(config.clone())
     }
diff --git a/src/transaction.rs b/src/transaction.rs
index ffa4021..1b650d8 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -11,11 +11,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::ops::RangeBounds;
-
+use crate::{Config, Error, Key, KvPair, Value};
 use futures::{Future, Poll, Stream};
-
-use {Config, Error, Key, KvPair, Value};
+use std::ops::RangeBounds;
 
 #[derive(Copy, Clone)]
 pub struct Timestamp(u64);
@@ -302,7 +300,7 @@ impl Future for Connect {
 pub struct Client {}
 
 impl Client {
-    #![cfg_attr(feature = "cargo-clippy", allow(new_ret_no_self))]
+    #![allow(clippy::new_ret_no_self)]
     pub fn new(config: &Config) -> Connect {
         Connect::new(config.clone())
     }