diff --git a/bellman/src/gadgets/blake2s.rs b/bellman/src/gadgets/blake2s.rs
index 9b6693b..8b1ff54 100644
--- a/bellman/src/gadgets/blake2s.rs
+++ b/bellman/src/gadgets/blake2s.rs
@@ -408,6 +408,7 @@ pub fn blake2s<E: ScalarEngine, CS: ConstraintSystem<E>>(
 #[cfg(test)]
 mod test {
     use blake2s_simd::Params as Blake2sParams;
+    use hex_literal::hex;
     use pairing::bls12_381::Bls12;
     use rand_core::{RngCore, SeedableRng};
     use rand_xorshift::XorShiftRng;
diff --git a/bellman/src/gadgets/sha256.rs b/bellman/src/gadgets/sha256.rs
index 0c8efea..1be898e 100644
--- a/bellman/src/gadgets/sha256.rs
+++ b/bellman/src/gadgets/sha256.rs
@@ -273,6 +273,7 @@ mod test {
     use super::*;
     use crate::gadgets::boolean::AllocatedBit;
     use crate::gadgets::test::TestConstraintSystem;
+    use hex_literal::hex;
     use pairing::bls12_381::Bls12;
     use rand_core::{RngCore, SeedableRng};
     use rand_xorshift::XorShiftRng;
diff --git a/bellman/src/lib.rs b/bellman/src/lib.rs
index a3b577b..ef13a83 100644
--- a/bellman/src/lib.rs
+++ b/bellman/src/lib.rs
@@ -135,19 +135,6 @@
 // Catch documentation errors caused by code changes.
 #![deny(intra_doc_link_resolution_failure)]
 
-#[cfg(feature = "multicore")]
-extern crate crossbeam;
-
-#[cfg(feature = "multicore")]
-extern crate num_cpus;
-
-#[cfg(test)]
-#[macro_use]
-extern crate hex_literal;
-
-#[cfg(test)]
-extern crate rand;
-
 pub mod domain;
 pub mod gadgets;
 #[cfg(feature = "groth16")]
diff --git a/ff/ff_derive/src/lib.rs b/ff/ff_derive/src/lib.rs
index 7cdaf91..d47ec12 100644
--- a/ff/ff_derive/src/lib.rs
+++ b/ff/ff_derive/src/lib.rs
@@ -2,17 +2,11 @@
 
 extern crate proc_macro;
 extern crate proc_macro2;
-extern crate syn;
-#[macro_use]
-extern crate quote;
-
-extern crate num_bigint;
-extern crate num_integer;
-extern crate num_traits;
 
 use num_bigint::BigUint;
 use num_integer::Integer;
 use num_traits::{One, ToPrimitive, Zero};
+use quote::quote;
 use quote::TokenStreamExt;
 use std::str::FromStr;
 
diff --git a/ff/src/lib.rs b/ff/src/lib.rs
index 6be25da..b50cbd5 100644
--- a/ff/src/lib.rs
+++ b/ff/src/lib.rs
@@ -4,10 +4,6 @@
 #![deny(intra_doc_link_resolution_failure)]
 #![allow(unused_imports)]
 
-#[cfg(feature = "derive")]
-#[macro_use]
-extern crate ff_derive;
-
 #[cfg(feature = "derive")]
 pub use ff_derive::*;
 
diff --git a/zcash_primitives/src/jubjub/mod.rs b/zcash_primitives/src/jubjub/mod.rs
index 555f3b9..9428600 100644
--- a/zcash_primitives/src/jubjub/mod.rs
+++ b/zcash_primitives/src/jubjub/mod.rs
@@ -469,6 +469,8 @@ impl JubjubBls12 {
 
 #[test]
 fn test_jubjub_bls12() {
+    use hex_literal::hex;
+
     let params = JubjubBls12::new();
 
     tests::test_suite::<Bls12>(&params);
diff --git a/zcash_primitives/src/lib.rs b/zcash_primitives/src/lib.rs
index 713ca2b..d882f5a 100644
--- a/zcash_primitives/src/lib.rs
+++ b/zcash_primitives/src/lib.rs
@@ -6,12 +6,7 @@
 // Catch documentation errors caused by code changes.
 #![deny(intra_doc_link_resolution_failure)]
 
-#[macro_use]
-extern crate lazy_static;
-
-#[cfg(test)]
-#[macro_use]
-extern crate hex_literal;
+use lazy_static::lazy_static;
 
 pub mod block;
 pub mod constants;
diff --git a/zcash_primitives/src/sapling.rs b/zcash_primitives/src/sapling.rs
index 4f57a43..da8b838 100644
--- a/zcash_primitives/src/sapling.rs
+++ b/zcash_primitives/src/sapling.rs
@@ -6,6 +6,7 @@ use crate::{
     primitives::Note,
 };
 use ff::{BitIterator, PrimeField, PrimeFieldRepr};
+use lazy_static::lazy_static;
 use pairing::bls12_381::{Bls12, Fr, FrRepr};
 use rand_core::{CryptoRng, RngCore};
 use std::io::{self, Read, Write};