diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8956f563..b98fe7cd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@ and this project adheres to Rust's notion of
 
 ### Removed
 - `halo2::arithmetic::BatchInvert` (use `ff::BatchInvert` instead).
+- `impl Default for halo2::poly::Rotation` (use `Rotation::cur()` instead).
 
 ## [0.1.0-beta.1] - 2021-09-24
 Initial beta release!
diff --git a/examples/simple-example.rs b/examples/simple-example.rs
index f75e6f5d..8e69daa5 100644
--- a/examples/simple-example.rs
+++ b/examples/simple-example.rs
@@ -65,9 +65,6 @@ struct FieldConfig {
     // This is important when building larger circuits, where columns are used by
     // multiple sets of instructions.
     s_mul: Selector,
-
-    /// The fixed column used to load constants.
-    constant: Column<Fixed>,
 }
 
 impl<F: FieldExt> FieldChip<F> {
@@ -125,7 +122,6 @@ impl<F: FieldExt> FieldChip<F> {
             advice,
             instance,
             s_mul,
-            constant,
         }
     }
 }
diff --git a/src/plonk.rs b/src/plonk.rs
index a31e6c6d..de916fe2 100644
--- a/src/plonk.rs
+++ b/src/plonk.rs
@@ -112,6 +112,7 @@ impl<C: CurveAffine> VerifyingKey<C> {
 
 /// Minimal representation of a verification key that can be used to identify
 /// its active contents.
+#[allow(dead_code)]
 #[derive(Debug)]
 pub struct PinnedVerificationKey<'a, C: CurveAffine> {
     base_modulus: &'static str,
diff --git a/src/plonk/circuit.rs b/src/plonk/circuit.rs
index f36d52e6..4ca4e16f 100644
--- a/src/plonk/circuit.rs
+++ b/src/plonk/circuit.rs
@@ -982,6 +982,7 @@ pub struct ConstraintSystem<F: Field> {
 }
 
 /// Represents the minimal parameters that determine a `ConstraintSystem`.
+#[allow(dead_code)]
 #[derive(Debug)]
 pub struct PinnedConstraintSystem<'a, F: Field> {
     num_fixed_columns: &'a usize,
diff --git a/src/plonk/lookup/prover.rs b/src/plonk/lookup/prover.rs
index 33aa36d7..6e7c60d3 100644
--- a/src/plonk/lookup/prover.rs
+++ b/src/plonk/lookup/prover.rs
@@ -30,14 +30,12 @@ pub(in crate::plonk) struct Permuted<C: CurveAffine> {
     permuted_input_poly: Polynomial<C::Scalar, Coeff>,
     permuted_input_coset: Polynomial<C::Scalar, ExtendedLagrangeCoeff>,
     permuted_input_blind: Blind<C::Scalar>,
-    permuted_input_commitment: C,
     unpermuted_table_expressions: Vec<Polynomial<C::Scalar, LagrangeCoeff>>,
     unpermuted_table_cosets: Vec<Polynomial<C::Scalar, ExtendedLagrangeCoeff>>,
     permuted_table_expression: Polynomial<C::Scalar, LagrangeCoeff>,
     permuted_table_poly: Polynomial<C::Scalar, Coeff>,
     permuted_table_coset: Polynomial<C::Scalar, ExtendedLagrangeCoeff>,
     permuted_table_blind: Blind<C::Scalar>,
-    permuted_table_commitment: C,
 }
 
 #[derive(Debug)]
@@ -46,7 +44,6 @@ pub(in crate::plonk) struct Committed<C: CurveAffine> {
     product_poly: Polynomial<C::Scalar, Coeff>,
     product_coset: Polynomial<C::Scalar, ExtendedLagrangeCoeff>,
     product_blind: Blind<C::Scalar>,
-    product_commitment: C,
 }
 
 pub(in crate::plonk) struct Constructed<C: CurveAffine> {
@@ -225,14 +222,12 @@ impl<F: FieldExt> Argument<F> {
             permuted_input_poly,
             permuted_input_coset,
             permuted_input_blind,
-            permuted_input_commitment,
             unpermuted_table_expressions,
             unpermuted_table_cosets,
             permuted_table_expression,
             permuted_table_poly,
             permuted_table_coset,
             permuted_table_blind,
-            permuted_table_commitment,
         })
     }
 }
@@ -393,7 +388,6 @@ impl<C: CurveAffine> Permuted<C> {
             permuted: self,
             product_poly: z,
             product_coset,
-            product_commitment,
             product_blind,
         })
     }
diff --git a/src/poly.rs b/src/poly.rs
index 8c43ee6c..d38ac729 100644
--- a/src/poly.rs
+++ b/src/poly.rs
@@ -288,12 +288,6 @@ impl<'a, F: Field, B: Basis> Mul<F> for Polynomial<F, B> {
 #[derive(Copy, Clone, Debug, PartialEq)]
 pub struct Rotation(pub i32);
 
-impl Default for Rotation {
-    fn default() -> Rotation {
-        Rotation(0)
-    }
-}
-
 impl Rotation {
     /// The current location in the evaluation domain
     pub fn cur() -> Rotation {
diff --git a/src/poly/commitment/prover.rs b/src/poly/commitment/prover.rs
index 00a6b523..211b60fe 100644
--- a/src/poly/commitment/prover.rs
+++ b/src/poly/commitment/prover.rs
@@ -143,9 +143,9 @@ pub fn create_proof<C: CurveAffine, E: EncodedChallenge<C>, T: TranscriptWrite<C
 
 fn parallel_generator_collapse<C: CurveAffine>(g: &mut [C], challenge: C::Scalar) {
     let len = g.len() / 2;
-    let (mut g_lo, g_hi) = g.split_at_mut(len);
+    let (g_lo, g_hi) = g.split_at_mut(len);
 
-    parallelize(&mut g_lo, |g_lo, start| {
+    parallelize(g_lo, |g_lo, start| {
         let g_hi = &g_hi[start..];
         let mut tmp = Vec::with_capacity(g_lo.len());
         for (g_lo, g_hi) in g_lo.iter().zip(g_hi.iter()) {
diff --git a/src/poly/domain.rs b/src/poly/domain.rs
index 1c785078..8f449359 100644
--- a/src/poly/domain.rs
+++ b/src/poly/domain.rs
@@ -409,13 +409,13 @@ impl<G: Group> EvaluationDomain<G> {
     ///
     /// `into_coset` should be set to `true` when moving into the coset,
     /// and `false` when moving out. This toggles the choice of `zeta`.
-    fn distribute_powers_zeta(&self, mut a: &mut [G], into_coset: bool) {
+    fn distribute_powers_zeta(&self, a: &mut [G], into_coset: bool) {
         let coset_powers = if into_coset {
             [self.g_coset, self.g_coset_inv]
         } else {
             [self.g_coset_inv, self.g_coset]
         };
-        parallelize(&mut a, |a, mut index| {
+        parallelize(a, |a, mut index| {
             for a in a {
                 // Distribute powers to move into/from coset
                 let i = index % (coset_powers.len() + 1);
@@ -544,6 +544,7 @@ impl<G: Group> EvaluationDomain<G> {
 }
 
 /// Represents the minimal parameters that determine an `EvaluationDomain`.
+#[allow(dead_code)]
 #[derive(Debug)]
 pub struct PinnedEvaluationDomain<'a, G: Group> {
     k: &'a u32,
diff --git a/src/poly/multiopen/prover.rs b/src/poly/multiopen/prover.rs
index ba5df952..bea21010 100644
--- a/src/poly/multiopen/prover.rs
+++ b/src/poly/multiopen/prover.rs
@@ -15,14 +15,6 @@ use group::Curve;
 use std::io;
 use std::marker::PhantomData;
 
-#[derive(Debug, Clone)]
-struct CommitmentData<C: CurveAffine> {
-    set_index: usize,
-    blind: Blind<C::Scalar>,
-    point_indices: Vec<usize>,
-    evals: Vec<C::Scalar>,
-}
-
 /// Create a multi-opening proof
 pub fn create_proof<'a, I, C: CurveAffine, E: EncodedChallenge<C>, T: TranscriptWrite<C, E>>(
     params: &Params<C>,
diff --git a/src/poly/multiopen/verifier.rs b/src/poly/multiopen/verifier.rs
index 5fca01fc..ea96a0b8 100644
--- a/src/poly/multiopen/verifier.rs
+++ b/src/poly/multiopen/verifier.rs
@@ -10,12 +10,6 @@ use super::{
 };
 use crate::arithmetic::{eval_polynomial, lagrange_interpolate, CurveAffine, FieldExt};
 use crate::transcript::{EncodedChallenge, TranscriptRead};
-#[derive(Debug, Clone)]
-struct CommitmentData<C: CurveAffine> {
-    set_index: usize,
-    point_indices: Vec<usize>,
-    evals: Vec<C::Scalar>,
-}
 
 /// Verify a multi-opening proof
 pub fn verify_proof<
diff --git a/tests/plonk_api.rs b/tests/plonk_api.rs
index 52667cc7..e432c58b 100644
--- a/tests/plonk_api.rs
+++ b/tests/plonk_api.rs
@@ -218,7 +218,7 @@ fn plonk_api() {
             layouter.assign_region(
                 || "public_input",
                 |mut region| {
-                    let value = region.assign_advice(|| "value", self.config.a, 0, || f())?;
+                    let value = region.assign_advice(|| "value", self.config.a, 0, &mut f)?;
                     region.assign_fixed(|| "public", self.config.sp, 0, || Ok(FF::one()))?;
 
                     Ok(value.cell())