diff --git a/src/poly/commitment.rs b/src/poly/commitment.rs
index c0d4520..787bd8b 100644
--- a/src/poly/commitment.rs
+++ b/src/poly/commitment.rs
@@ -87,8 +87,8 @@ impl<F: FieldExt, T> Deref for ChallengeScalar<F, T> {
 }
 
 #[derive(Clone, Copy, Debug)]
-pub(crate) struct X6 {}
-pub(crate) type ChallengeX6<F> = ChallengeScalar<F, X6>;
+pub(crate) struct Z {}
+pub(crate) type ChallengeZ<F> = ChallengeScalar<F, Z>;
 
 /// These are the public parameters for the polynomial commitment scheme.
 #[derive(Debug)]
@@ -346,16 +346,16 @@ fn test_opening_proof() {
 
     let mut transcript = Transcript::<_, DummyHash<_>, DummyHash<_>>::new();
     transcript.absorb_point(&p).unwrap();
-    let x = ChallengeX6::get(&mut transcript);
+    let z = ChallengeZ::get(&mut transcript);
     // Evaluate the polynomial
-    let v = eval_polynomial(&px, *x);
+    let v = eval_polynomial(&px, *z);
 
     transcript.absorb_base(Fp::from_bytes(&v.to_bytes()).unwrap()); // unlikely to fail since p ~ q
 
     loop {
         let mut transcript_dup = transcript.clone();
 
-        let opening_proof = Proof::create(&params, &mut transcript, &px, blind, x);
+        let opening_proof = Proof::create(&params, &mut transcript, &px, blind, z);
         if let Ok(opening_proof) = opening_proof {
             // Verify the opening proof
             let mut commitment_msm = params.empty_msm();
@@ -365,7 +365,7 @@ fn test_opening_proof() {
                     &params,
                     params.empty_msm(),
                     &mut transcript_dup,
-                    x,
+                    z,
                     commitment_msm,
                     v,
                 )
diff --git a/src/poly/commitment/prover.rs b/src/poly/commitment/prover.rs
index 0f02978..22d8956 100644
--- a/src/poly/commitment/prover.rs
+++ b/src/poly/commitment/prover.rs
@@ -1,7 +1,7 @@
 use ff::Field;
 
 use super::super::{Coeff, Error, Polynomial};
-use super::{Blind, Challenge, ChallengeScalar, ChallengeX6, Params, Proof};
+use super::{Blind, Challenge, ChallengeScalar, ChallengeZ, Params, Proof};
 use crate::arithmetic::{
     best_multiexp, compute_inner_product, parallelize, small_multiexp, Curve, CurveAffine, FieldExt,
 };
@@ -26,7 +26,7 @@ impl<C: CurveAffine> Proof<C> {
         transcript: &mut Transcript<C, HBase, HScalar>,
         px: &Polynomial<C::Scalar, Coeff>,
         blind: Blind<C::Scalar>,
-        x: ChallengeX6<C::Scalar>,
+        z: ChallengeZ<C::Scalar>,
     ) -> Result<Self, Error>
     where
         HBase: Hasher<C::Base>,
@@ -61,7 +61,7 @@ impl<C: CurveAffine> Proof<C> {
             let mut cur = C::Scalar::one();
             for _ in 0..(1 << params.k) {
                 b.push(cur);
-                cur *= &x;
+                cur *= &z;
             }
         }
 
diff --git a/src/poly/commitment/verifier.rs b/src/poly/commitment/verifier.rs
index b9001fa..3c34928 100644
--- a/src/poly/commitment/verifier.rs
+++ b/src/poly/commitment/verifier.rs
@@ -1,7 +1,7 @@
 use ff::Field;
 
 use super::super::Error;
-use super::{Challenge, ChallengeScalar, ChallengeX6, Params, Proof, MSM};
+use super::{Challenge, ChallengeScalar, ChallengeZ, Params, Proof, MSM};
 use crate::transcript::{Hasher, Transcript};
 
 use crate::arithmetic::{best_multiexp, Curve, CurveAffine, FieldExt};
@@ -71,7 +71,7 @@ impl<C: CurveAffine> Proof<C> {
         params: &'a Params<C>,
         mut msm: MSM<'a, C>,
         transcript: &mut Transcript<C, HBase, HScalar>,
-        x: ChallengeX6<C::Scalar>,
+        z: ChallengeZ<C::Scalar>,
         mut commitment_msm: MSM<'a, C>,
         v: C::Scalar,
     ) -> Result<Guard<'a, C>, Error>
@@ -164,7 +164,7 @@ impl<C: CurveAffine> Proof<C> {
         // The computation of [z1] (G + H) happens in either Guard::use_challenges()
         // or Guard::use_g().
 
-        let b = compute_b(*x, &challenges, &challenges_inv);
+        let b = compute_b(*z, &challenges, &challenges_inv);
 
         let neg_z1 = -self.z1;
 
diff --git a/src/poly/multiopen/prover.rs b/src/poly/multiopen/prover.rs
index e14c6db..890ea21 100644
--- a/src/poly/multiopen/prover.rs
+++ b/src/poly/multiopen/prover.rs
@@ -1,5 +1,5 @@
 use super::super::{
-    commitment::{self, Blind, ChallengeScalar, ChallengeX6, Params},
+    commitment::{self, Blind, ChallengeScalar, ChallengeZ, Params},
     Coeff, Error, Polynomial,
 };
 use super::{construct_intermediate_sets, Proof, ProverQuery, Query};
@@ -113,11 +113,11 @@ impl<C: CurveAffine> Proof<C> {
                 .absorb_point(&f_commitment)
                 .map_err(|_| Error::SamplingError)?;
 
-            let x_6 = ChallengeX6::get(&mut transcript);
+            let z = ChallengeZ::get(&mut transcript);
 
             let q_evals: Vec<C::Scalar> = q_polys
                 .iter()
-                .map(|poly| eval_polynomial(poly.as_ref().unwrap(), *x_6))
+                .map(|poly| eval_polynomial(poly.as_ref().unwrap(), *z))
                 .collect();
 
             for eval in q_evals.iter() {
@@ -137,7 +137,7 @@ impl<C: CurveAffine> Proof<C> {
             );
 
             if let Ok(opening) =
-                commitment::Proof::create(&params, &mut transcript, &f_poly, f_blind_try, x_6)
+                commitment::Proof::create(&params, &mut transcript, &f_poly, f_blind_try, z)
             {
                 break (opening, q_evals);
             } else {
diff --git a/src/poly/multiopen/verifier.rs b/src/poly/multiopen/verifier.rs
index c265d0f..858216f 100644
--- a/src/poly/multiopen/verifier.rs
+++ b/src/poly/multiopen/verifier.rs
@@ -1,7 +1,7 @@
 use ff::Field;
 
 use super::super::{
-    commitment::{ChallengeScalar, ChallengeX6, Guard, Params, MSM},
+    commitment::{ChallengeScalar, ChallengeZ, Guard, Params, MSM},
     Error,
 };
 use super::{construct_intermediate_sets, Proof, Query, VerifierQuery};
@@ -77,15 +77,15 @@ impl<C: CurveAffine> Proof<C> {
             .absorb_point(&self.f_commitment)
             .map_err(|_| Error::SamplingError)?;
 
-        // Sample a challenge x_6 for checking that f(X) was committed to
+        // Sample a challenge z for checking that f(X) was committed to
         // correctly.
-        let x_6 = ChallengeX6::get(transcript);
+        let z = ChallengeZ::get(transcript);
 
         for eval in self.q_evals.iter() {
             transcript.absorb_scalar(*eval);
         }
 
-        // We can compute the expected msm_eval at x_6 using the q_evals provided
+        // We can compute the expected msm_eval at z using the q_evals provided
         // by the prover and from x_5
         let msm_eval = point_sets
             .iter()
@@ -95,16 +95,16 @@ impl<C: CurveAffine> Proof<C> {
                 C::Scalar::zero(),
                 |msm_eval, ((points, evals), proof_eval)| {
                     let r_poly = lagrange_interpolate(points, evals);
-                    let r_eval = eval_polynomial(&r_poly, *x_6);
+                    let r_eval = eval_polynomial(&r_poly, *z);
                     let eval = points.iter().fold(*proof_eval - &r_eval, |eval, point| {
-                        eval * &(*x_6 - point).invert().unwrap()
+                        eval * &(*z - point).invert().unwrap()
                     });
                     msm_eval * &x_5 + &eval
                 },
             );
 
         // Sample a challenge x_7 that we will use to collapse the openings of
-        // the various remaining polynomials at x_6 together.
+        // the various remaining polynomials at z together.
         let x_7 = ChallengeScalar::<_, ()>::get(transcript);
 
         // Compute the final commitment that has to be opened
@@ -121,7 +121,7 @@ impl<C: CurveAffine> Proof<C> {
 
         // Verify the opening proof
         self.opening
-            .verify(params, msm, transcript, x_6, commitment_msm, msm_eval)
+            .verify(params, msm, transcript, z, commitment_msm, msm_eval)
     }
 }