diff --git a/spartan_parallel/src/scalar/mod.rs b/spartan_parallel/src/scalar/mod.rs
index a8a73968..138a2259 100644
--- a/spartan_parallel/src/scalar/mod.rs
+++ b/spartan_parallel/src/scalar/mod.rs
@@ -13,7 +13,7 @@ use std::{
   cmp::Eq,
   hash::Hash,
   iter::{Product, Sum},
-  ops::{Add, Mul, MulAssign, Neg, Sub},
+  ops::{Add, AddAssign, Mul, MulAssign, Neg, Sub, SubAssign},
 };
 use subtle::{Choice, ConditionallySelectable, ConstantTimeEq, CtOption};
 use zeroize::Zeroize;
@@ -35,6 +35,9 @@ pub trait SpartanExtensionField:
   + Add<Output = Self>
   + Sub<Output = Self>
   + Mul<Output = Self>
+  + AddAssign<Self>
+  + SubAssign<Self>
+  + MulAssign<Self>
   + Sum
   + Product
   + Clone
diff --git a/spartan_parallel/src/sumcheck.rs b/spartan_parallel/src/sumcheck.rs
index e181fdf2..249b1abd 100644
--- a/spartan_parallel/src/sumcheck.rs
+++ b/spartan_parallel/src/sumcheck.rs
@@ -155,7 +155,7 @@ impl<S: SpartanExtensionField> SumcheckInstanceProof<S> {
       let len = poly_A.len() / 2;
       for i in 0..len {
         // eval 0: bound_func is A(low)
-        eval_point_0 = eval_point_0 + comb_func(&poly_A[i], &poly_B[i], &poly_C[i]);
+        eval_point_0 += comb_func(&poly_A[i], &poly_B[i], &poly_C[i]);
 
         // eval 2: bound_func is -A(low) + 2*A(high)
         let poly_A_bound_point = poly_A[len + i] + poly_A[len + i] - poly_A[i];