diff --git a/examples/decode.rs b/examples/decode.rs
index e8ce586..b5d6a99 100644
--- a/examples/decode.rs
+++ b/examples/decode.rs
@@ -3,9 +3,7 @@
 
 #![deny(warnings)]
 
-extern crate toml;
-#[macro_use]
-extern crate serde_derive;
+use serde_derive::Deserialize;
 
 /// This is what we're going to decode into. Each field is optional, meaning
 /// that it doesn't have to be present in TOML.
diff --git a/examples/enum_external.rs b/examples/enum_external.rs
index e2ac4f8..a7dd84a 100644
--- a/examples/enum_external.rs
+++ b/examples/enum_external.rs
@@ -3,9 +3,7 @@
 
 #![deny(warnings)]
 
-extern crate toml;
-#[macro_use]
-extern crate serde_derive;
+use serde_derive::Deserialize;
 
 /// This is what we're going to decode into.
 #[derive(Debug, Deserialize)]
diff --git a/examples/toml2json.rs b/examples/toml2json.rs
index 12c3f1c..1b90c9f 100644
--- a/examples/toml2json.rs
+++ b/examples/toml2json.rs
@@ -1,8 +1,5 @@
 #![deny(warnings)]
 
-extern crate serde_json;
-extern crate toml;
-
 use std::env;
 use std::fs::File;
 use std::io;
diff --git a/src/datetime.rs b/src/datetime.rs
index b77621a..61eb3b1 100644
--- a/src/datetime.rs
+++ b/src/datetime.rs
@@ -65,13 +65,13 @@ enum Offset {
 }
 
 impl fmt::Debug for Datetime {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Display::fmt(self, f)
     }
 }
 
 impl fmt::Display for Datetime {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         if let Some(ref date) = self.date {
             write!(f, "{}", date)?;
         }
@@ -89,13 +89,13 @@ impl fmt::Display for Datetime {
 }
 
 impl fmt::Display for Date {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{:04}-{:02}-{:02}", self.year, self.month, self.day)
     }
 }
 
 impl fmt::Display for Time {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{:02}:{:02}:{:02}", self.hour, self.minute, self.second)?;
         if self.nanosecond != 0 {
             let s = format!("{:09}", self.nanosecond);
@@ -106,7 +106,7 @@ impl fmt::Display for Time {
 }
 
 impl fmt::Display for Offset {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
             Offset::Z => write!(f, "Z"),
             Offset::Custom { hours, minutes } => write!(f, "{:+03}:{:02}", hours, minutes),
@@ -207,7 +207,7 @@ impl FromStr for Datetime {
                 let mut end = whole.len();
                 for (i, byte) in whole.bytes().enumerate() {
                     match byte {
-                        b'0'...b'9' => {
+                        b'0'..=b'9' => {
                             if i < 9 {
                                 let p = 10_u32.pow(8 - i as u32);
                                 nanosecond += p * (byte - b'0') as u32;
@@ -298,7 +298,7 @@ impl FromStr for Datetime {
     }
 }
 
-fn digit(chars: &mut str::Chars) -> Result<u8, DatetimeParseError> {
+fn digit(chars: &mut str::Chars<'_>) -> Result<u8, DatetimeParseError> {
     match chars.next() {
         Some(c) if '0' <= c && c <= '9' => Ok(c as u8 - b'0'),
         _ => Err(DatetimeParseError { _private: () }),
@@ -328,7 +328,7 @@ impl<'de> de::Deserialize<'de> for Datetime {
         impl<'de> de::Visitor<'de> for DatetimeVisitor {
             type Value = Datetime;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a TOML datetime")
             }
 
@@ -362,7 +362,7 @@ impl<'de> de::Deserialize<'de> for DatetimeKey {
         impl<'de> de::Visitor<'de> for FieldVisitor {
             type Value = ();
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a valid datetime field")
             }
 
@@ -397,7 +397,7 @@ impl<'de> de::Deserialize<'de> for DatetimeFromString {
         impl<'de> de::Visitor<'de> for Visitor {
             type Value = DatetimeFromString;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("string containing a datetime")
             }
 
@@ -417,7 +417,7 @@ impl<'de> de::Deserialize<'de> for DatetimeFromString {
 }
 
 impl fmt::Display for DatetimeParseError {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         "failed to parse datetime".fmt(f)
     }
 }
diff --git a/src/de.rs b/src/de.rs
index 291da3b..077c008 100644
--- a/src/de.rs
+++ b/src/de.rs
@@ -41,9 +41,7 @@ where
 /// # Examples
 ///
 /// ```
-/// #[macro_use]
-/// extern crate serde_derive;
-/// extern crate toml;
+/// use serde_derive::Deserialize;
 ///
 /// #[derive(Deserialize)]
 /// struct Config {
@@ -265,7 +263,7 @@ impl<'de, 'b> de::Deserializer<'de> for &'b mut Deserializer<'de> {
         }
     }
 
-    forward_to_deserialize_any! {
+    serde::forward_to_deserialize_any! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
         bytes byte_buf map struct unit newtype_struct
         ignored_any unit_struct tuple_struct tuple option identifier
@@ -495,7 +493,7 @@ impl<'de, 'b> de::Deserializer<'de> for MapVisitor<'de, 'b> {
         visitor.visit_newtype_struct(self)
     }
 
-    forward_to_deserialize_any! {
+    serde::forward_to_deserialize_any! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
         bytes byte_buf map struct unit identifier
         ignored_any unit_struct tuple_struct tuple enum
@@ -525,7 +523,7 @@ impl<'de> de::Deserializer<'de> for StrDeserializer<'de> {
         }
     }
 
-    forward_to_deserialize_any! {
+    serde::forward_to_deserialize_any! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
         bytes byte_buf map struct option unit newtype_struct
         ignored_any unit_struct tuple_struct tuple enum identifier
@@ -699,7 +697,7 @@ impl<'de> de::Deserializer<'de> for ValueDeserializer<'de> {
         visitor.visit_newtype_struct(self)
     }
 
-    forward_to_deserialize_any! {
+    serde::forward_to_deserialize_any! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
         bytes byte_buf map unit identifier
         ignored_any unit_struct tuple_struct tuple
@@ -796,7 +794,7 @@ impl<'de> de::Deserializer<'de> for DatetimeFieldDeserializer {
         visitor.visit_borrowed_str(datetime::FIELD)
     }
 
-    forward_to_deserialize_any! {
+    serde::forward_to_deserialize_any! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
         bytes byte_buf map struct option unit newtype_struct
         ignored_any unit_struct tuple_struct tuple enum identifier
@@ -1520,7 +1518,7 @@ impl<'a> Deserializer<'a> {
     fn array(&mut self) -> Result<(Span, Vec<Value<'a>>), Error> {
         let mut ret = Vec::new();
 
-        let intermediate = |me: &mut Deserializer| {
+        let intermediate = |me: &mut Deserializer<'_>| {
             loop {
                 me.eat_whitespace()?;
                 if !me.eat(Token::Newline)? && !me.eat_comment()? {
@@ -1775,7 +1773,7 @@ impl Error {
 }
 
 impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.inner.kind {
             ErrorKind::UnexpectedEof => "unexpected eof encountered".fmt(f)?,
             ErrorKind::InvalidCharInString(c) => write!(
diff --git a/src/lib.rs b/src/lib.rs
index 7e8dbbe..30ee3bc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -77,9 +77,7 @@
 //! An example of deserializing with TOML is:
 //!
 //! ```rust
-//! #[macro_use]
-//! extern crate serde_derive;
-//! extern crate toml;
+//! use serde_derive::Deserialize;
 //!
 //! #[derive(Deserialize)]
 //! struct Config {
@@ -113,9 +111,7 @@
 //! You can serialize types in a similar fashion:
 //!
 //! ```rust
-//! #[macro_use]
-//! extern crate serde_derive;
-//! extern crate toml;
+//! use serde_derive::Serialize;
 //!
 //! #[derive(Serialize)]
 //! struct Config {
@@ -150,11 +146,7 @@
 
 #![doc(html_root_url = "https://docs.rs/toml/0.5")]
 #![deny(missing_docs)]
-
-#[macro_use]
-extern crate serde;
-#[cfg(feature = "preserve_order")]
-extern crate linked_hash_map;
+#![warn(rust_2018_idioms)]
 
 pub mod map;
 pub mod value;
diff --git a/src/macros.rs b/src/macros.rs
index 9f11733..0731afe 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -7,11 +7,8 @@ use crate::value::{Array, Table, Value};
 /// [`toml::Value`]: value/enum.Value.html
 ///
 /// ```rust
-/// #[macro_use]
-/// extern crate toml;
-///
 /// fn main() {
-///     let cargo_toml = toml! {
+///     let cargo_toml = toml::toml! {
 ///         [package]
 ///         name = "toml"
 ///         version = "0.4.5"
diff --git a/src/map.rs b/src/map.rs
index 3a2473a..054961d 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -140,7 +140,7 @@ impl Map<String, Value> {
 
     /// Gets the given key's corresponding entry in the map for in-place
     /// manipulation.
-    pub fn entry<S>(&mut self, key: S) -> Entry
+    pub fn entry<S>(&mut self, key: S) -> Entry<'_>
     where
         S: Into<String>,
     {
@@ -169,7 +169,7 @@ impl Map<String, Value> {
 
     /// Gets an iterator over the entries of the map.
     #[inline]
-    pub fn iter(&self) -> Iter {
+    pub fn iter(&self) -> Iter<'_> {
         Iter {
             iter: self.map.iter(),
         }
@@ -177,7 +177,7 @@ impl Map<String, Value> {
 
     /// Gets a mutable iterator over the entries of the map.
     #[inline]
-    pub fn iter_mut(&mut self) -> IterMut {
+    pub fn iter_mut(&mut self) -> IterMut<'_> {
         IterMut {
             iter: self.map.iter_mut(),
         }
@@ -185,7 +185,7 @@ impl Map<String, Value> {
 
     /// Gets an iterator over the keys of the map.
     #[inline]
-    pub fn keys(&self) -> Keys {
+    pub fn keys(&self) -> Keys<'_> {
         Keys {
             iter: self.map.keys(),
         }
@@ -193,7 +193,7 @@ impl Map<String, Value> {
 
     /// Gets an iterator over the values of the map.
     #[inline]
-    pub fn values(&self) -> Values {
+    pub fn values(&self) -> Values<'_> {
         Values {
             iter: self.map.values(),
         }
@@ -253,7 +253,7 @@ where
 
 impl Debug for Map<String, Value> {
     #[inline]
-    fn fmt(&self, formatter: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         self.map.fmt(formatter)
     }
 }
@@ -285,7 +285,7 @@ impl<'de> de::Deserialize<'de> for Map<String, Value> {
         impl<'de> de::Visitor<'de> for Visitor {
             type Value = Map<String, Value>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a map")
             }
 
diff --git a/src/ser.rs b/src/ser.rs
index 2dcd962..328772a 100644
--- a/src/ser.rs
+++ b/src/ser.rs
@@ -12,8 +12,7 @@
 //! may use the `tables_last` function in this module like so:
 //!
 //! ```rust
-//! # #[macro_use] extern crate serde_derive;
-//! # extern crate toml;
+//! # use serde_derive::Serialize;
 //! # use std::collections::HashMap;
 //! #[derive(Serialize)]
 //! struct Manifest {
@@ -56,9 +55,7 @@ where
 /// # Examples
 ///
 /// ```
-/// #[macro_use]
-/// extern crate serde_derive;
-/// extern crate toml;
+/// use serde_derive::Serialize;
 ///
 /// #[derive(Serialize)]
 /// struct Config {
@@ -442,7 +439,7 @@ impl<'a> Serializer<'a> {
     }
 
     // recursive implementation of `emit_key` above
-    fn _emit_key(&mut self, state: &State) -> Result<(), Error> {
+    fn _emit_key(&mut self, state: &State<'_>) -> Result<(), Error> {
         match *state {
             State::End => Ok(()),
             State::Array {
@@ -479,7 +476,7 @@ impl<'a> Serializer<'a> {
 
     fn emit_array(&mut self, first: &Cell<bool>, len: Option<usize>) -> Result<(), Error> {
         match (len, &self.settings.array) {
-            (Some(0...1), _) | (_, &None) => {
+            (Some(0..=1), _) | (_, &None) => {
                 if first.get() {
                     self.dst.push_str("[")
                 } else {
@@ -517,7 +514,7 @@ impl<'a> Serializer<'a> {
 
     fn escape_key(&mut self, key: &str) -> Result<(), Error> {
         let ok = key.chars().all(|c| match c {
-            'a'...'z' | 'A'...'Z' | '0'...'9' | '-' | '_' => true,
+            'a'..='z' | 'A'..='Z' | '0'..='9' | '-' | '_' => true,
             _ => false,
         });
         if ok {
@@ -666,7 +663,7 @@ impl<'a> Serializer<'a> {
         Ok(())
     }
 
-    fn emit_table_header(&mut self, state: &State) -> Result<(), Error> {
+    fn emit_table_header(&mut self, state: &State<'_>) -> Result<(), Error> {
         let array_of_tables = match *state {
             State::End => return Ok(()),
             State::Array { .. } => true,
@@ -730,7 +727,7 @@ impl<'a> Serializer<'a> {
         Ok(())
     }
 
-    fn emit_key_part(&mut self, key: &State) -> Result<bool, Error> {
+    fn emit_key_part(&mut self, key: &State<'_>) -> Result<bool, Error> {
         match *key {
             State::Array { parent, .. } => self.emit_key_part(parent),
             State::End => Ok(true),
@@ -997,7 +994,7 @@ impl<'a, 'b> ser::SerializeSeq for SerializeSeq<'a, 'b> {
         match self.type_.get() {
             Some("table") => return Ok(()),
             Some(_) => match (self.len, &self.ser.settings.array) {
-                (Some(0...1), _) | (_, &None) => {
+                (Some(0..=1), _) | (_, &None) => {
                     self.ser.dst.push_str("]");
                 }
                 (_, &Some(ref a)) => {
@@ -1531,7 +1528,7 @@ impl ser::Serializer for StringExtractor {
 }
 
 impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match *self {
             Error::UnsupportedType => "unsupported Rust type".fmt(f),
             Error::KeyNotString => "map key was not a string".fmt(f),
@@ -1584,8 +1581,7 @@ enum Category {
 /// helper can be used like so:
 ///
 /// ```rust
-/// # #[macro_use] extern crate serde_derive;
-/// # extern crate toml;
+/// # use serde_derive::Serialize;
 /// # use std::collections::HashMap;
 /// #[derive(Serialize)]
 /// struct Manifest {
diff --git a/src/spanned.rs b/src/spanned.rs
index fb476ee..cd02c87 100644
--- a/src/spanned.rs
+++ b/src/spanned.rs
@@ -1,8 +1,5 @@
 //! ```
-//! #[macro_use]
-//! extern crate serde_derive;
-//!
-//! extern crate toml;
+//! use serde_derive::Deserialize;
 //! use toml::Spanned;
 //!
 //! #[derive(Deserialize)]
@@ -93,7 +90,7 @@ where
         {
             type Value = Spanned<T>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a TOML spanned")
             }
 
diff --git a/src/tokens.rs b/src/tokens.rs
index 6413ce1..f9d3eb4 100644
--- a/src/tokens.rs
+++ b/src/tokens.rs
@@ -294,8 +294,8 @@ impl<'a> Tokenizer<'a> {
         &mut self,
         delim: char,
         start: usize,
-        new_ch: &mut FnMut(
-            &mut Tokenizer,
+        new_ch: &mut dyn FnMut(
+            &mut Tokenizer<'_>,
             &mut MaybeString,
             bool,
             usize,
@@ -514,7 +514,7 @@ impl MaybeString {
         }
     }
 
-    fn into_cow(self, input: &str) -> Cow<str> {
+    fn into_cow(self, input: &str) -> Cow<'_, str> {
         match self {
             MaybeString::NotEscaped(start) => Cow::Borrowed(&input[start..]),
             MaybeString::Owned(s) => Cow::Owned(s),
@@ -665,9 +665,9 @@ mod tests {
 
     #[test]
     fn all() {
-        fn t(input: &str, expected: &[((usize, usize), Token, &str)]) {
+        fn t(input: &str, expected: &[((usize, usize), Token<'_>, &str)]) {
             let mut tokens = Tokenizer::new(input);
-            let mut actual: Vec<((usize, usize), Token, &str)> = Vec::new();
+            let mut actual: Vec<((usize, usize), Token<'_>, &str)> = Vec::new();
             while let Some((span, token)) = tokens.next().unwrap() {
                 actual.push((span.into(), token, &input[span.start..span.end]));
             }
diff --git a/src/value.rs b/src/value.rs
index 0e463ec..8f2c6c6 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -391,7 +391,7 @@ where
 }
 
 impl fmt::Display for Value {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         crate::ser::to_string(self)
             .expect("Unable to represent value as string")
             .fmt(f)
@@ -462,7 +462,7 @@ impl<'de> de::Deserialize<'de> for Value {
         impl<'de> de::Visitor<'de> for ValueVisitor {
             type Value = Value;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("any valid TOML value")
             }
 
@@ -628,7 +628,7 @@ impl<'de> de::Deserializer<'de> for Value {
         visitor.visit_newtype_struct(self)
     }
 
-    forward_to_deserialize_any! {
+    serde::forward_to_deserialize_any! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string unit seq
         bytes byte_buf map unit_struct tuple_struct struct
         tuple ignored_any identifier
@@ -1060,7 +1060,7 @@ impl<'a, 'de> de::DeserializeSeed<'de> for DatetimeOrTable<'a> {
 impl<'a, 'de> de::Visitor<'de> for DatetimeOrTable<'a> {
     type Value = bool;
 
-    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+    fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
         formatter.write_str("a string key")
     }