diff --git a/Cargo.toml b/Cargo.toml
index 6e88e54..4c5a04d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,6 +10,7 @@ version = "0.0.1"
 
 [dependencies]
 rand = "0.4.0"
+ff = { version = "0.4", features = ["derive"] }
 # sha3 = "0.8"
 
 [dependencies.merlin] 
@@ -18,6 +19,7 @@ version = "1.0.0"
 
 [dependencies.pairing]
 git = "https://github.com/burdges/pairing"
-branch = "derives_borrows_etc0"
+branch = "master-hashing-derives_borrows_etc0"
+# branch = "derives_borrows_etc0"
 # git = "https://github.com/mmaker/pairing"
 # branch = "master"
diff --git a/src/lib.rs b/src/lib.rs
index abb1a0a..5c7c497 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,6 +3,9 @@
 // #![feature(generic_associated_types)]
 #![feature(associated_type_defaults)]
 
+// #[macro_use]
+extern crate ff;
+
 extern crate merlin;
 extern crate pairing;
 extern crate rand;
@@ -10,7 +13,8 @@ extern crate rand;
 
 use std::borrow::Borrow;
 
-use pairing::{CurveAffine, CurveProjective, Engine, Field, PrimeField, SqrtField};
+use ff::{Field, PrimeField, ScalarEngine, SqrtField}; // PrimeFieldDecodingError, PrimeFieldRepr
+use pairing::{CurveAffine, CurveProjective, Engine};
 use rand::{Rand, Rng};
 
 pub mod single;
@@ -69,8 +73,8 @@ impl<'a> From<&'a [u8]> for Message {
 /// We also extract two functions users may with to override:
 /// random scalar generation and hashing to the singature curve.
 pub trait EngineBLS {
-    type Engine: Engine<Fr = Self::Scalar>;
-    type Scalar: PrimeField + SqrtField;
+    type Engine: Engine + ScalarEngine<Fr = Self::Scalar>;
+    type Scalar: PrimeField + SqrtField; // = <Self::Engine as ScalarEngine>::Fr;
 
     /// Group where BLS public keys live
     /// 
@@ -182,7 +186,7 @@ pub struct UsualBLS<E: Engine>(pub E);
 
 impl<E: Engine> EngineBLS for UsualBLS<E> {
     type Engine = E;
-    type Scalar = <Self::Engine as Engine>::Fr;
+    type Scalar = <Self::Engine as ScalarEngine>::Fr;
     type PublicKeyGroup = E::G1;
     type SignatureGroup = E::G2;
 
@@ -223,7 +227,7 @@ pub struct TinyBLS<E: Engine>(pub E);
 
 impl<E: Engine> EngineBLS for TinyBLS<E> {
     type Engine = E;
-    type Scalar = <Self::Engine as Engine>::Fr;
+    type Scalar = <Self::Engine as ScalarEngine>::Fr;
     type PublicKeyGroup = E::G2;
     type SignatureGroup = E::G1;
 
diff --git a/src/single.rs b/src/single.rs
index 1f255e4..cd7e49e 100644
--- a/src/single.rs
+++ b/src/single.rs
@@ -23,7 +23,8 @@
 //!  https://github.com/ebfull/pairing/pull/87#issuecomment-402397091
 //!  https://github.com/poanetwork/hbbft/blob/38178af1244ddeca27f9d23750ca755af6e886ee/src/crypto/serde_impl.rs#L95
 
-use pairing::{CurveAffine, CurveProjective, Field};  // Engine, PrimeField, SqrtField
+use ff::{Field}; // PrimeField, ScalarEngine, SqrtField
+use pairing::{CurveAffine, CurveProjective};  // Engine, PrimeField, SqrtField
 use rand::{Rng, thread_rng};
 // use rand::prelude::*; // ThreadRng,thread_rng
 // use rand_chacha::ChaChaRng;