diff --git a/phf/Cargo.toml b/phf/Cargo.toml
index 1071c63c..85f98320 100644
--- a/phf/Cargo.toml
+++ b/phf/Cargo.toml
@@ -5,6 +5,7 @@ version = "0.7.24"
 license = "MIT"
 description = "Runtime support for perfect hash function data structures"
 repository = "https://github.com/sfackler/rust-phf"
+edition = "2018"
 
 [lib]
 name = "phf"
diff --git a/phf/src/lib.rs b/phf/src/lib.rs
index 28e6b86b..389aabe9 100644
--- a/phf/src/lib.rs
+++ b/phf/src/lib.rs
@@ -44,10 +44,6 @@
 #[cfg(not(feature = "core"))]
 extern crate std as core;
 
-extern crate phf_shared;
-#[cfg(feature = "macros")]
-extern crate phf_macros;
-
 #[cfg(feature = "macros")]
 pub use phf_macros::*;
 
@@ -55,13 +51,13 @@ use core::ops::Deref;
 
 pub use phf_shared::PhfHash;
 #[doc(inline)]
-pub use map::Map;
+pub use self::map::Map;
 #[doc(inline)]
-pub use set::Set;
+pub use self::set::Set;
 #[doc(inline)]
-pub use ordered_map::OrderedMap;
+pub use self::ordered_map::OrderedMap;
 #[doc(inline)]
-pub use ordered_set::OrderedSet;
+pub use self::ordered_set::OrderedSet;
 
 pub mod map;
 pub mod set;
diff --git a/phf/src/map.rs b/phf/src/map.rs
index efabf31b..bd743516 100644
--- a/phf/src/map.rs
+++ b/phf/src/map.rs
@@ -5,7 +5,7 @@ use core::slice;
 use core::fmt;
 use core::iter::IntoIterator;
 use phf_shared::{self, PhfHash};
-use Slice;
+use crate::Slice;
 
 /// An immutable map constructed at compile time.
 ///
diff --git a/phf/src/ordered_map.rs b/phf/src/ordered_map.rs
index 82567a67..239ce95f 100644
--- a/phf/src/ordered_map.rs
+++ b/phf/src/ordered_map.rs
@@ -6,7 +6,7 @@ use core::fmt;
 use core::slice;
 use phf_shared::{self, PhfHash};
 
-use Slice;
+use crate::Slice;
 
 /// An order-preserving immutable map constructed at compile time.
 ///
diff --git a/phf/src/ordered_set.rs b/phf/src/ordered_set.rs
index 622fad9e..dbff7de1 100644
--- a/phf/src/ordered_set.rs
+++ b/phf/src/ordered_set.rs
@@ -2,8 +2,7 @@
 use core::borrow::Borrow;
 use core::iter::IntoIterator;
 use core::fmt;
-use ordered_map;
-use {PhfHash, OrderedMap};
+use crate::{ordered_map, PhfHash, OrderedMap};
 
 /// An order-preserving immutable set constructed at compile time.
 ///
diff --git a/phf/src/set.rs b/phf/src/set.rs
index 04ed9a00..9588d4a7 100644
--- a/phf/src/set.rs
+++ b/phf/src/set.rs
@@ -3,9 +3,7 @@ use core::borrow::Borrow;
 use core::iter::IntoIterator;
 use core::fmt;
 
-use PhfHash;
-use map;
-use Map;
+use crate::{map, Map, PhfHash};
 
 /// An immutable set constructed at compile time.
 ///
diff --git a/phf_codegen/test/Cargo.toml b/phf_codegen/test/Cargo.toml
index 8c4d662f..492c37c7 100644
--- a/phf_codegen/test/Cargo.toml
+++ b/phf_codegen/test/Cargo.toml
@@ -3,6 +3,7 @@ name = "phf_codegen_test"
 authors = ["Steven Fackler <sfackler@gmail.com>"]
 version = "0.0.0"
 build = "build.rs"
+edition = "2018"
 
 [dependencies]
 unicase = "2.4.0"
diff --git a/phf_codegen/test/src/lib.rs b/phf_codegen/test/src/lib.rs
index 16be9c82..2ae3a55c 100644
--- a/phf_codegen/test/src/lib.rs
+++ b/phf_codegen/test/src/lib.rs
@@ -1,6 +1,3 @@
-extern crate phf;
-extern crate unicase;
-
 #[cfg(test)]
 mod test {
     use unicase::UniCase;
diff --git a/phf_generator/Cargo.toml b/phf_generator/Cargo.toml
index 6c4451fe..b3b41bc0 100644
--- a/phf_generator/Cargo.toml
+++ b/phf_generator/Cargo.toml
@@ -5,6 +5,7 @@ version = "0.7.24"
 license = "MIT"
 description = "PHF generation logic"
 repository = "https://github.com/sfackler/rust-phf"
+edition = "2018"
 
 [dependencies]
 rand = "0.6"
diff --git a/phf_shared/Cargo.toml b/phf_shared/Cargo.toml
index b63ea601..1bafcd8c 100644
--- a/phf_shared/Cargo.toml
+++ b/phf_shared/Cargo.toml
@@ -5,6 +5,7 @@ version = "0.7.24"
 license = "MIT"
 description = "Support code shared by PHF libraries"
 repository = "https://github.com/sfackler/rust-phf"
+edition = "2018"
 
 [lib]
 name = "phf_shared"