diff --git a/z3-sys/tests/lib.rs b/z3-sys/tests/lib.rs
index c6b137cb..302748fa 100644
--- a/z3-sys/tests/lib.rs
+++ b/z3-sys/tests/lib.rs
@@ -1,5 +1,3 @@
-extern crate z3_sys;
-
 use std::ffi::{CStr, CString};
 use z3_sys::*;
 
diff --git a/z3/src/ast.rs b/z3/src/ast.rs
index 6fe354dc..7b2e5ba2 100644
--- a/z3/src/ast.rs
+++ b/z3/src/ast.rs
@@ -1,5 +1,6 @@
 //! Abstract syntax tree (AST).
 
+use log::debug;
 use std::borrow::Borrow;
 use std::cmp::{Eq, PartialEq};
 use std::convert::{TryFrom, TryInto};
diff --git a/z3/src/config.rs b/z3/src/config.rs
index 2a1e3b97..4b711020 100644
--- a/z3/src/config.rs
+++ b/z3/src/config.rs
@@ -1,3 +1,4 @@
+use log::debug;
 use std::ffi::CString;
 
 use z3_sys::*;
diff --git a/z3/src/context.rs b/z3/src/context.rs
index 9ecab83e..6adcaeff 100644
--- a/z3/src/context.rs
+++ b/z3/src/context.rs
@@ -1,3 +1,4 @@
+use log::debug;
 use std::ffi::CString;
 
 use z3_sys::*;
diff --git a/z3/src/lib.rs b/z3/src/lib.rs
index 772fe9f8..b81d1b3f 100644
--- a/z3/src/lib.rs
+++ b/z3/src/lib.rs
@@ -6,13 +6,6 @@
 #![warn(clippy::doc_markdown)]
 #![deny(missing_debug_implementations)]
 
-#[macro_use]
-extern crate log;
-
-extern crate z3_sys;
-
-extern crate num;
-
 use std::ffi::CString;
 use z3_sys::*;
 pub use z3_sys::{AstKind, GoalPrec, SortKind};
diff --git a/z3/src/solver.rs b/z3/src/solver.rs
index b7f2b06f..a78e1fcb 100644
--- a/z3/src/solver.rs
+++ b/z3/src/solver.rs
@@ -1,3 +1,4 @@
+use log::debug;
 use std::ffi::{CStr, CString};
 use std::fmt;
 
diff --git a/z3/tests/lib.rs b/z3/tests/lib.rs
index f78fb895..ae5d56af 100644
--- a/z3/tests/lib.rs
+++ b/z3/tests/lib.rs
@@ -1,15 +1,10 @@
-extern crate env_logger;
-#[macro_use]
-extern crate log;
-
-extern crate z3;
+use log::info;
 use std::convert::TryInto;
 use std::ops::Add;
 use std::time::Duration;
 use z3::ast::{Array, Ast, Bool, Int, BV};
 use z3::*;
 
-extern crate num;
 use num::{bigint::BigInt, rational::BigRational};
 use std::str::FromStr;
 
diff --git a/z3/tests/objectives.rs b/z3/tests/objectives.rs
index 1ee40d59..5644f2be 100644
--- a/z3/tests/objectives.rs
+++ b/z3/tests/objectives.rs
@@ -1,4 +1,3 @@
-extern crate z3;
 use z3::ast::Ast;
 use z3::*;
 
diff --git a/z3/tests/ops.rs b/z3/tests/ops.rs
index cb0fe2c1..cb531b76 100644
--- a/z3/tests/ops.rs
+++ b/z3/tests/ops.rs
@@ -1,5 +1,3 @@
-extern crate z3;
-
 use z3::{
     ast,
     ast::{Array, Ast, AstKind, Bool, Dynamic, Float, Int, Real, BV},
diff --git a/z3/tests/semver_tests.rs b/z3/tests/semver_tests.rs
index 6717e8e3..25079735 100644
--- a/z3/tests/semver_tests.rs
+++ b/z3/tests/semver_tests.rs
@@ -1,9 +1,4 @@
-extern crate env_logger;
-#[macro_use]
-extern crate log;
-extern crate semver;
-extern crate z3;
-
+use log::info;
 use semver::{Version, VersionReq};
 use std::collections::HashMap;
 use z3::ast::Ast;