diff --git a/halo2_proofs/src/helpers.rs b/halo2_proofs/src/helpers.rs
index f58ec9b100..e8521aa7ff 100644
--- a/halo2_proofs/src/helpers.rs
+++ b/halo2_proofs/src/helpers.rs
@@ -48,6 +48,10 @@ pub fn field_to_bn<F: FieldExt>(f: &F) -> BigUint {
 
 /// Input a big integer `bn`, compute a field element `f`
 /// such that `f == bn % F::MODULUS`.
+/// Require:
+/// - bn is less than 512 bits.
+/// Return:
+/// - bn mod F::MODULUS when bn > F::MODULUS
 pub fn bn_to_field<F: FieldExt>(bn: &BigUint) -> F {
     let mut buf = bn.to_bytes_le();
     buf.resize(64, 0u8);
diff --git a/halo2_proofs/src/poly/kzg/commitment.rs b/halo2_proofs/src/poly/kzg/commitment.rs
index 27d188aa5c..08665667b3 100644
--- a/halo2_proofs/src/poly/kzg/commitment.rs
+++ b/halo2_proofs/src/poly/kzg/commitment.rs
@@ -21,12 +21,12 @@ use super::msm::MSMKZG;
 /// These are the public parameters for the polynomial commitment scheme.
 #[derive(Debug, Clone)]
 pub struct ParamsKZG<E: Engine> {
-    pub(crate) k: u32,
+    pub k: u32,
     pub n: u64,
-    pub(crate) g: Vec<E::G1Affine>,
+    pub g: Vec<E::G1Affine>,
     pub g_lagrange: Vec<E::G1Affine>,
-    pub(crate) g2: E::G2Affine,
-    pub(crate) s_g2: E::G2Affine,
+    pub g2: E::G2Affine,
+    pub s_g2: E::G2Affine,
 }
 
 /// Umbrella commitment scheme construction for all KZG variants