diff --git a/src/plonk.rs b/src/plonk.rs
index afe16d8..1f29f2b 100644
--- a/src/plonk.rs
+++ b/src/plonk.rs
@@ -449,7 +449,7 @@ fn test_proving() {
             &params,
             &srs,
             &circuit,
-            aux_lagrange_polys.clone(),
+            &aux_lagrange_polys.clone(),
         )
         .expect("proof generation should not fail");
 
diff --git a/src/plonk/prover.rs b/src/plonk/prover.rs
index eb6fd08..7809f49 100644
--- a/src/plonk/prover.rs
+++ b/src/plonk/prover.rs
@@ -24,7 +24,7 @@ impl<C: CurveAffine> Proof<C> {
         params: &Params<C>,
         srs: &SRS<C>,
         circuit: &ConcreteCircuit,
-        aux_lagrange_polys: Vec<Polynomial<C::Scalar, LagrangeCoeff>>,
+        aux_lagrange_polys: &[Polynomial<C::Scalar, LagrangeCoeff>],
     ) -> Result<Self, Error> {
         struct WitnessCollection<F: Field> {
             advice: Vec<Polynomial<F, LagrangeCoeff>>,
@@ -143,7 +143,10 @@ impl<C: CurveAffine> Proof<C> {
         let aux_polys: Vec<_> = aux_lagrange_polys
             .clone()
             .into_iter()
-            .map(|poly| domain.lagrange_to_coeff(poly))
+            .map(|poly| {
+                let lagrange_vec = domain.lagrange_from_vec(poly.to_vec());
+                domain.lagrange_to_coeff(lagrange_vec)
+            })
             .collect();
 
         let aux_cosets: Vec<_> = meta