diff --git a/Cargo.toml b/Cargo.toml
index 25c9445..0ad9658 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -36,14 +36,12 @@ harness = false
 
 [dependencies]
 backtrace = { version = "0.3", optional = true }
-bitvec = "0.18"
 subtle = "2.3"
-crossbeam-utils = "0.7"
-ff = "0.8"
-metrics = "=0.13.0-alpha.13"
-metrics-macros = "=0.1.0-alpha.9"
+crossbeam-utils = "0.8"
+ff = "0.9"
+metrics = "0.14.2"
 num_cpus = "1.13"
-rand = "0.7"
+rand = "0.8"
 blake2b_simd = "0.5"
 lazy_static = "1.4.0"
 static_assertions = "1.1.0"
diff --git a/src/pasta/fields/fp.rs b/src/pasta/fields/fp.rs
index 665bc5c..4e876cf 100644
--- a/src/pasta/fields/fp.rs
+++ b/src/pasta/fields/fp.rs
@@ -1,7 +1,7 @@
-use bitvec::{array::BitArray, order::Lsb0};
 use core::convert::TryInto;
 use core::fmt;
 use core::ops::{Add, Mul, Neg, Sub};
+use ff::FieldBits;
 use lazy_static::lazy_static;
 use rand::RngCore;
 use subtle::{Choice, ConditionallySelectable, ConstantTimeEq, CtOption};
@@ -550,7 +550,7 @@ impl ff::PrimeField for Fp {
         self.to_bytes()
     }
 
-    fn to_le_bits(&self) -> BitArray<Lsb0, Self::ReprBits> {
+    fn to_le_bits(&self) -> FieldBits<Self::ReprBits> {
         let bytes = self.to_bytes();
 
         #[cfg(not(target_pointer_width = "64"))]
@@ -573,21 +573,21 @@ impl ff::PrimeField for Fp {
             u64::from_le_bytes(bytes[24..32].try_into().unwrap()),
         ];
 
-        BitArray::new(limbs)
+        FieldBits::new(limbs)
     }
 
     fn is_odd(&self) -> bool {
         self.to_bytes()[0] & 1 == 1
     }
 
-    fn char_le_bits() -> BitArray<Lsb0, Self::ReprBits> {
+    fn char_le_bits() -> FieldBits<Self::ReprBits> {
         #[cfg(not(target_pointer_width = "64"))]
         {
-            BitArray::new(MODULUS_LIMBS_32)
+            FieldBits::new(MODULUS_LIMBS_32)
         }
 
         #[cfg(target_pointer_width = "64")]
-        BitArray::new(MODULUS.0)
+        FieldBits::new(MODULUS.0)
     }
 
     fn multiplicative_generator() -> Self {
diff --git a/src/pasta/fields/fq.rs b/src/pasta/fields/fq.rs
index 79791d1..61deaa1 100644
--- a/src/pasta/fields/fq.rs
+++ b/src/pasta/fields/fq.rs
@@ -1,7 +1,7 @@
-use bitvec::{array::BitArray, order::Lsb0};
 use core::convert::TryInto;
 use core::fmt;
 use core::ops::{Add, Mul, Neg, Sub};
+use ff::FieldBits;
 use lazy_static::lazy_static;
 use rand::RngCore;
 use subtle::{Choice, ConditionallySelectable, ConstantTimeEq, CtOption};
@@ -550,7 +550,7 @@ impl ff::PrimeField for Fq {
         self.to_bytes()
     }
 
-    fn to_le_bits(&self) -> BitArray<Lsb0, Self::ReprBits> {
+    fn to_le_bits(&self) -> FieldBits<Self::ReprBits> {
         let bytes = self.to_bytes();
 
         #[cfg(not(target_pointer_width = "64"))]
@@ -573,21 +573,21 @@ impl ff::PrimeField for Fq {
             u64::from_le_bytes(bytes[24..32].try_into().unwrap()),
         ];
 
-        BitArray::new(limbs)
+        FieldBits::new(limbs)
     }
 
     fn is_odd(&self) -> bool {
         self.to_bytes()[0] & 1 == 1
     }
 
-    fn char_le_bits() -> BitArray<Lsb0, Self::ReprBits> {
+    fn char_le_bits() -> FieldBits<Self::ReprBits> {
         #[cfg(not(target_pointer_width = "64"))]
         {
-            BitArray::new(MODULUS_LIMBS_32)
+            FieldBits::new(MODULUS_LIMBS_32)
         }
 
         #[cfg(target_pointer_width = "64")]
-        BitArray::new(MODULUS.0)
+        FieldBits::new(MODULUS.0)
     }
 
     fn multiplicative_generator() -> Self {