diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 93896e7..ea91ef1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,11 +23,11 @@ jobs:
         if: matrix.rust == 'nightly'
 
   msrv:
-    name: Rust 1.15.0
+    name: Rust 1.31.0
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: dtolnay/rust-toolchain@1.15.0
+      - uses: dtolnay/rust-toolchain@1.31.0
       - run: cargo build
       - run: cargo build --features small
 
diff --git a/Cargo.toml b/Cargo.toml
index 8af8867..856fe8c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,6 +8,7 @@ repository = "https://github.com/dtolnay/ryu"
 documentation = "https://docs.rs/ryu"
 readme = "README.md"
 build = "build.rs"
+edition = "2018"
 
 [features]
 # Use smaller lookup tables. Instead of storing every required power of
diff --git a/README.md b/README.md
index e990313..44ec366 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 [![Build Status](https://img.shields.io/github/workflow/status/dtolnay/ryu/CI/master)](https://github.com/dtolnay/ryu/actions?query=branch%3Amaster)
 [![Latest Version](https://img.shields.io/crates/v/ryu.svg)](https://crates.io/crates/ryu)
 [![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/ryu)
-[![Rustc Version 1.15+](https://img.shields.io/badge/rustc-1.15+-lightgray.svg)](https://blog.rust-lang.org/2017/02/02/Rust-1.15.html)
+[![Rustc Version 1.31+](https://img.shields.io/badge/rustc-1.31+-lightgray.svg)](https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html)
 
 Pure Rust implementation of Ryū, an algorithm to quickly convert floating point
 numbers to decimal strings.
@@ -15,7 +15,7 @@ under the creative commons CC-BY-SA license.
 This Rust implementation is a line-by-line port of Ulf Adams' implementation in
 C, [https://github.com/ulfjack/ryu][upstream].
 
-*Requirements: this crate supports any compiler version back to rustc 1.15; it
+*Requirements: this crate supports any compiler version back to rustc 1.31; it
 uses nothing from the Rust standard library so is usable from no_std crates.*
 
 [paper]: https://dl.acm.org/citation.cfm?id=3192369
diff --git a/benches/bench.rs b/benches/bench.rs
index 04d9bee..f7a0d90 100644
--- a/benches/bench.rs
+++ b/benches/bench.rs
@@ -2,7 +2,6 @@
 
 #![feature(test)]
 
-extern crate ryu;
 extern crate test;
 
 macro_rules! benches {
@@ -12,8 +11,6 @@ macro_rules! benches {
             $(
                 #[bench]
                 fn $name(b: &mut Bencher) {
-                    use ryu;
-
                     let mut buf = ryu::Buffer::new();
 
                     b.iter(move || {
diff --git a/examples/upstream_benchmark.rs b/examples/upstream_benchmark.rs
index 7b91265..437855b 100644
--- a/examples/upstream_benchmark.rs
+++ b/examples/upstream_benchmark.rs
@@ -1,8 +1,5 @@
 // cargo run --example upstream_benchmark --release
 
-extern crate rand;
-extern crate ryu;
-
 use rand::{Rng, SeedableRng};
 
 const SAMPLES: usize = 10000;
diff --git a/src/buffer/mod.rs b/src/buffer/mod.rs
index d524de6..df21fe0 100644
--- a/src/buffer/mod.rs
+++ b/src/buffer/mod.rs
@@ -1,10 +1,7 @@
-use core::{mem, slice, str};
-
+use crate::raw;
 #[cfg(maybe_uninit)]
 use core::mem::MaybeUninit;
-
-use raw;
-
+use core::{mem, slice, str};
 #[cfg(feature = "no-panic")]
 use no_panic::no_panic;
 
@@ -16,7 +13,7 @@ const NEG_INFINITY: &'static str = "-inf";
 ///
 /// ## Example
 ///
-/// ```edition2018
+/// ```
 /// let mut buffer = ryu::Buffer::new();
 /// let printed = buffer.format_finite(1.234);
 /// assert_eq!(printed, "1.234");
diff --git a/src/d2s.rs b/src/d2s.rs
index cebef96..213860f 100644
--- a/src/d2s.rs
+++ b/src/d2s.rs
@@ -18,20 +18,17 @@
 // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.
 
-use core::ptr;
-
-#[cfg(maybe_uninit)]
-use core::mem::MaybeUninit;
-
+use crate::common::*;
+#[cfg(not(feature = "small"))]
+use crate::d2s_full_table::*;
+use crate::d2s_intrinsics::*;
+#[cfg(feature = "small")]
+use crate::d2s_small_table::*;
 #[cfg(not(maybe_uninit))]
 use core::mem;
-
-use common::*;
-#[cfg(not(feature = "small"))]
-use d2s_full_table::*;
-use d2s_intrinsics::*;
-#[cfg(feature = "small")]
-use d2s_small_table::*;
+#[cfg(maybe_uninit)]
+use core::mem::MaybeUninit;
+use core::ptr;
 
 pub const DOUBLE_MANTISSA_BITS: u32 = 52;
 pub const DOUBLE_EXPONENT_BITS: u32 = 11;
diff --git a/src/d2s_small_table.rs b/src/d2s_small_table.rs
index fc4a1a2..c6f0973 100644
--- a/src/d2s_small_table.rs
+++ b/src/d2s_small_table.rs
@@ -18,9 +18,9 @@
 // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.
 
-use common::*;
+use crate::common::*;
 #[cfg(not(integer128))]
-use d2s_intrinsics::*;
+use crate::d2s_intrinsics::*;
 
 pub static DOUBLE_POW5_TABLE: [u64; 26] = [
     1,
diff --git a/src/f2s.rs b/src/f2s.rs
index 4ad50a1..0633e8e 100644
--- a/src/f2s.rs
+++ b/src/f2s.rs
@@ -18,7 +18,7 @@
 // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.
 
-use common::*;
+use crate::common::*;
 
 pub const FLOAT_MANTISSA_BITS: u32 = 23;
 pub const FLOAT_EXPONENT_BITS: u32 = 8;
diff --git a/src/lib.rs b/src/lib.rs
index f7fddb2..8974ed7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,7 +13,7 @@
 //!
 //! # Example
 //!
-//! ```edition2018
+//! ```
 //! fn main() {
 //!     let mut buffer = ryu::Buffer::new();
 //!     let printed = buffer.format(1.234);
@@ -88,9 +88,6 @@
     allow(cast_lossless, many_single_char_names, unreadable_literal,)
 )]
 
-#[cfg(feature = "no-panic")]
-extern crate no_panic;
-
 mod buffer;
 mod common;
 mod d2s;
@@ -103,9 +100,9 @@ mod digit_table;
 mod f2s;
 mod pretty;
 
-pub use buffer::{Buffer, Float};
+pub use crate::buffer::{Buffer, Float};
 
 /// Unsafe functions that mirror the API of the C implementation of Ryū.
 pub mod raw {
-    pub use pretty::{format32, format64};
+    pub use crate::pretty::{format32, format64};
 }
diff --git a/src/pretty/exponent.rs b/src/pretty/exponent.rs
index f10643f..84053d5 100644
--- a/src/pretty/exponent.rs
+++ b/src/pretty/exponent.rs
@@ -1,7 +1,6 @@
+use crate::digit_table::*;
 use core::ptr;
 
-use digit_table::*;
-
 #[cfg_attr(feature = "no-panic", inline)]
 pub unsafe fn write_exponent3(mut k: isize, mut result: *mut u8) -> usize {
     let sign = k < 0;
diff --git a/src/pretty/mantissa.rs b/src/pretty/mantissa.rs
index 4280232..e5fc202 100644
--- a/src/pretty/mantissa.rs
+++ b/src/pretty/mantissa.rs
@@ -1,7 +1,6 @@
+use crate::digit_table::*;
 use core::ptr;
 
-use digit_table::*;
-
 #[cfg_attr(feature = "no-panic", inline)]
 pub unsafe fn write_mantissa_long(mut output: u64, mut result: *mut u8) {
     if (output >> 32) != 0 {
diff --git a/src/pretty/mod.rs b/src/pretty/mod.rs
index 1e51343..5eed13c 100644
--- a/src/pretty/mod.rs
+++ b/src/pretty/mod.rs
@@ -1,15 +1,12 @@
 mod exponent;
 mod mantissa;
 
-use core::{mem, ptr};
-
 use self::exponent::*;
 use self::mantissa::*;
-use common;
-use d2s;
-use d2s::*;
-use f2s::*;
-
+use crate::common;
+use crate::d2s::{self, *};
+use crate::f2s::*;
+use core::{mem, ptr};
 #[cfg(feature = "no-panic")]
 use no_panic::no_panic;
 
@@ -37,7 +34,7 @@ use no_panic::no_panic;
 ///
 /// ## Example
 ///
-/// ```edition2018
+/// ```
 /// use std::{mem::MaybeUninit, slice, str};
 ///
 /// let f = 1.234f64;
@@ -144,7 +141,7 @@ pub unsafe fn format64(f: f64, result: *mut u8) -> usize {
 ///
 /// ## Example
 ///
-/// ```edition2018
+/// ```
 /// use std::{mem::MaybeUninit, slice, str};
 ///
 /// let f = 1.234f32;
diff --git a/tests/d2s_table_test.rs b/tests/d2s_table_test.rs
index 8f27726..9e30e71 100644
--- a/tests/d2s_table_test.rs
+++ b/tests/d2s_table_test.rs
@@ -20,8 +20,6 @@
 
 #![allow(dead_code)]
 
-extern crate core;
-
 #[path = "../src/common.rs"]
 mod common;
 
diff --git a/tests/d2s_test.rs b/tests/d2s_test.rs
index a4118be..32a7821 100644
--- a/tests/d2s_test.rs
+++ b/tests/d2s_test.rs
@@ -18,9 +18,6 @@
 // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.
 
-extern crate rand;
-extern crate ryu;
-
 #[macro_use]
 mod macros;
 
diff --git a/tests/exhaustive.rs b/tests/exhaustive.rs
index 5c36969..e97045e 100644
--- a/tests/exhaustive.rs
+++ b/tests/exhaustive.rs
@@ -1,8 +1,5 @@
 #![cfg(exhaustive)]
 
-extern crate num_cpus;
-extern crate ryu;
-
 use std::str;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Arc;
diff --git a/tests/f2s_test.rs b/tests/f2s_test.rs
index e6aaf5b..57eba43 100644
--- a/tests/f2s_test.rs
+++ b/tests/f2s_test.rs
@@ -18,9 +18,6 @@
 // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 // KIND, either express or implied.
 
-extern crate rand;
-extern crate ryu;
-
 #[macro_use]
 mod macros;