diff --git a/src/field/extension_field/target.rs b/src/field/extension_field/target.rs
index 712c6103..c00470ac 100644
--- a/src/field/extension_field/target.rs
+++ b/src/field/extension_field/target.rs
@@ -19,15 +19,14 @@ impl<const D: usize> ExtensionTarget<D> {
     pub fn frobenius<F: Extendable<D>>(&self, builder: &mut CircuitBuilder<F, D>) -> Self {
         let arr = self.to_target_array();
         let k = (F::ORDER - 1) / (D as u64);
-        let z0 = builder.constant(F::Extension::W.exp(k));
-        let mut z = builder.one();
-        let mut res = [builder.zero(); D];
-        for i in 0..D {
-            res[i] = builder.mul(arr[i], z);
-            z = builder.mul(z, z0);
+        let zs = (0..D as u64).map(|i| builder.constant(F::Extension::W.exp(k * i)));
+
+        let mut res = Vec::with_capacity(D);
+        for (z, a) in zs.zip(arr) {
+            res.push(builder.mul(z, a));
         }
 
-        Self(res)
+        res.try_into().unwrap()
     }
 
     pub fn from_range(gate: usize, range: Range<usize>) -> Self {