diff --git a/Cargo.toml b/Cargo.toml
index 55440d9..0c5472a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,6 +2,7 @@
 name = "simple-filesystem"
 version = "0.0.1"
 authors = ["WangRunji <wangrunji0408@163.com>"]
+edition = "2018"
 
 [[bin]]
 name = "mksfs"
@@ -10,7 +11,7 @@ required-features = ["std"]
 
 [dependencies]
 bit-vec = { default-features = false, git = "https://github.com/AltSysrq/bit-vec.git" } # default-features contains 'std'
-static_assertions = "0.2.5"
+static_assertions = "0.3"
 spin = "0.4"
 
 [features]
diff --git a/src/bin/mksfs.rs b/src/bin/mksfs.rs
index cfee1a8..63ccf46 100644
--- a/src/bin/mksfs.rs
+++ b/src/bin/mksfs.rs
@@ -1,5 +1,3 @@
-extern crate simple_filesystem;
-
 use std::env;
 use std::fs;
 use std::io::{Read, Write, Result};
diff --git a/src/blocked_device.rs b/src/blocked_device.rs
index 98e1bf2..5e1ff0a 100644
--- a/src/blocked_device.rs
+++ b/src/blocked_device.rs
@@ -1,5 +1,5 @@
-use util::*;
-use vfs::Device;
+use crate::util::*;
+use crate::vfs::Device;
 
 /// Device which can only R/W in blocks
 pub trait BlockedDevice: Send {
diff --git a/src/file.rs b/src/file.rs
index 6c1886e..6cc6684 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -1,4 +1,4 @@
-use vfs::{INode, Result, FileInfo};
+use crate::vfs::{INode, Result, FileInfo};
 use alloc::{sync::Arc, string::String};
 
 pub struct File {
diff --git a/src/lib.rs b/src/lib.rs
index 94ae27b..f2f4a73 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,17 +1,10 @@
+#![cfg_attr(not(any(test, feature = "std")), no_std)]
 #![feature(alloc)]
 #![feature(const_fn)]
 #![feature(nll)]
-#![cfg_attr(target_arch = "riscv", feature(match_default_bindings))]
-#![no_std]
+#![feature(extern_crate_item_prelude)]
 
-#[cfg(any(test, feature = "std"))]
-#[macro_use]
-extern crate std;
 extern crate alloc;
-extern crate bit_vec;
-#[macro_use]
-extern crate static_assertions;
-extern crate spin;
 
 #[cfg(not(test))]
 macro_rules! eprintln {
@@ -30,9 +23,9 @@ mod structs;
 #[cfg(test)]
 mod tests;
 
-pub use sfs::*;
-pub use vfs::*;
-pub use blocked_device::BlockedDevice;
+pub use crate::sfs::*;
+pub use crate::vfs::*;
+pub use crate::blocked_device::BlockedDevice;
 
 #[cfg(any(test, feature = "std"))]
 pub mod std_impl {
diff --git a/src/sfs.rs b/src/sfs.rs
index 41bdcf4..37c4214 100644
--- a/src/sfs.rs
+++ b/src/sfs.rs
@@ -4,11 +4,11 @@ use core::mem::uninitialized;
 use core::slice;
 use core::fmt::{Debug, Formatter, Error};
 use core::any::Any;
-use dirty::Dirty;
-use structs::*;
-use vfs::{self, Device, INode, FileSystem};
-use util::*;
 use spin::{Mutex, RwLock};
+use crate::dirty::Dirty;
+use crate::structs::*;
+use crate::vfs::{self, Device, INode, FileSystem};
+use crate::util::*;
 
 impl Device {
     fn read_block(&mut self, id: BlockId, offset: usize, buf: &mut [u8]) -> vfs::Result<()> {
@@ -622,7 +622,7 @@ impl vfs::FileSystem for SimpleFileSystem {
 impl Drop for SimpleFileSystem {
     /// Auto sync when drop
     fn drop(&mut self) {
-        use vfs::FileSystem;
+        use crate::vfs::FileSystem;
         self.sync().expect("failed to sync");
     }
 }
diff --git a/src/structs.rs b/src/structs.rs
index e5e14a0..ed4a7d7 100644
--- a/src/structs.rs
+++ b/src/structs.rs
@@ -4,6 +4,7 @@ use core::slice;
 use core::mem::{size_of_val, size_of};
 use core::fmt::{Debug, Formatter, Error};
 use alloc::str;
+use static_assertions::const_assert;
 
 /// On-disk superblock
 #[repr(C)]
diff --git a/src/tests.rs b/src/tests.rs
index 1cbbe5a..98efd35 100644
--- a/src/tests.rs
+++ b/src/tests.rs
@@ -3,10 +3,10 @@ use std::io::{Read, Write, Seek, SeekFrom};
 use std::boxed::Box;
 use std::sync::Arc;
 use std::mem::uninitialized;
-use super::sfs::*;
-use super::vfs::*;
-use super::vfs::INode;
-use super::structs::{DiskEntry, AsBuf};
+use crate::sfs::*;
+use crate::vfs::*;
+use crate::vfs::INode;
+use crate::structs::{DiskEntry, AsBuf};
 
 fn _open_sample_file() -> Arc<SimpleFileSystem> {
     fs::copy("sfs.img", "test.img").expect("failed to open sfs.img");