diff --git a/src/provider/pasta.rs b/src/provider/pasta.rs
index 9009b99..1197154 100644
--- a/src/provider/pasta.rs
+++ b/src/provider/pasta.rs
@@ -178,8 +178,8 @@ macro_rules! impl_traits {
         $name::Scalar::from_bytes_wide(&bytes_arr)
       }
 
-      fn to_bytes(s: &Self) -> Vec<u8> {
-        s.to_repr().as_ref().to_vec()
+      fn to_bytes(&self) -> Vec<u8> {
+        self.to_repr().as_ref().to_vec()
       }
     }
 
diff --git a/src/spartan/sumcheck.rs b/src/spartan/sumcheck.rs
index d32d07b..d84eb9b 100644
--- a/src/spartan/sumcheck.rs
+++ b/src/spartan/sumcheck.rs
@@ -38,10 +38,9 @@ impl<G: Group> SumcheckProof<G> {
         return Err(NovaError::InvalidSumcheckProof);
       }
 
-      // check if G_k(0) + G_k(1) = e
-      if poly.eval_at_zero() + poly.eval_at_one() != e {
-        return Err(NovaError::InvalidSumcheckProof);
-      }
+      // we do not need to check if poly(0) + poly(1) = e, as
+      // decompress() call above already ensures that hods
+      debug_assert_eq!(poly.eval_at_zero() + poly.eval_at_one(), e);
 
       // append the prover's message to the transcript
       poly.append_to_transcript(b"poly", transcript);
diff --git a/src/traits/mod.rs b/src/traits/mod.rs
index d8f5caf..6e7a166 100644
--- a/src/traits/mod.rs
+++ b/src/traits/mod.rs
@@ -228,7 +228,7 @@ pub trait PrimeFieldExt: PrimeField {
   fn from_uniform(bytes: &[u8]) -> Self;
 
   /// Returns a vector of bytes representing the scalar
-  fn to_bytes(s: &Self) -> Vec<u8>;
+  fn to_bytes(&self) -> Vec<u8>;
 }
 
 impl<G: Group<Scalar = F>, F: PrimeField + PrimeFieldExt> AppendToTranscriptTrait<G> for F {