diff --git a/src/plonk.rs b/src/plonk.rs
index e0accee..244d205 100644
--- a/src/plonk.rs
+++ b/src/plonk.rs
@@ -91,6 +91,10 @@ impl<C: CurveAffine> VerifyingKey<C> {
     }
 }
 
+#[derive(Clone, Copy, Debug)]
+struct Theta;
+type ChallengeTheta<F> = ChallengeScalar<F, Theta>;
+
 #[derive(Clone, Copy, Debug)]
 struct Beta;
 type ChallengeBeta<F> = ChallengeScalar<F, Beta>;
diff --git a/src/plonk/prover.rs b/src/plonk/prover.rs
index bce29c1..3c5830f 100644
--- a/src/plonk/prover.rs
+++ b/src/plonk/prover.rs
@@ -3,7 +3,8 @@ use std::iter;
 
 use super::{
     circuit::{Advice, Assignment, Circuit, Column, ConstraintSystem, Fixed},
-    permutation, ChallengeBeta, ChallengeGamma, ChallengeX, ChallengeY, Error, Proof, ProvingKey,
+    permutation, ChallengeBeta, ChallengeGamma, ChallengeTheta, ChallengeX, ChallengeY, Error,
+    Proof, ProvingKey,
 };
 use crate::arithmetic::{eval_polynomial, Curve, CurveAffine, FieldExt};
 use crate::poly::{
@@ -168,6 +169,9 @@ impl<C: CurveAffine> Proof<C> {
             })
             .collect();
 
+        // Sample theta challenge for keeping lookup columns linearly independent
+        let theta = ChallengeTheta::<C::Scalar>::get(&mut transcript);
+
         // Sample beta challenge
         let beta = ChallengeBeta::get(&mut transcript);
 
diff --git a/src/plonk/verifier.rs b/src/plonk/verifier.rs
index 4925dbd..c005c9d 100644
--- a/src/plonk/verifier.rs
+++ b/src/plonk/verifier.rs
@@ -1,7 +1,10 @@
 use ff::Field;
 use std::iter;
 
-use super::{ChallengeBeta, ChallengeGamma, ChallengeX, ChallengeY, Error, Proof, VerifyingKey};
+use super::{
+    ChallengeBeta, ChallengeGamma, ChallengeTheta, ChallengeX, ChallengeY, Error, Proof,
+    VerifyingKey,
+};
 use crate::arithmetic::{CurveAffine, FieldExt};
 use crate::poly::{
     commitment::{Guard, Params, MSM},
@@ -45,6 +48,9 @@ impl<'a, C: CurveAffine> Proof<C> {
                 .map_err(|_| Error::TranscriptError)?;
         }
 
+        // Sample theta challenge for keeping lookup columns linearly independent
+        let theta = ChallengeTheta::get(&mut transcript);
+
         // Sample beta challenge
         let beta = ChallengeBeta::get(&mut transcript);
 
@@ -72,7 +78,7 @@ impl<'a, C: CurveAffine> Proof<C> {
 
         // This check ensures the circuit is satisfied so long as the polynomial
         // commitments open to the correct values.
-        self.check_hx(params, vk, beta, gamma, y, x)?;
+        self.check_hx(params, vk, theta, beta, gamma, y, x)?;
 
         for eval in self
             .advice_evals
@@ -189,6 +195,7 @@ impl<'a, C: CurveAffine> Proof<C> {
         &self,
         params: &'a Params<C>,
         vk: &VerifyingKey<C>,
+        theta: ChallengeTheta<C::Scalar>,
         beta: ChallengeBeta<C::Scalar>,
         gamma: ChallengeGamma<C::Scalar>,
         y: ChallengeY<C::Scalar>,