diff --git a/halo2_gadgets/src/poseidon/primitives/mds.rs b/halo2_gadgets/src/poseidon/primitives/mds.rs
index f04df0fb58..892ee11f6b 100644
--- a/halo2_gadgets/src/poseidon/primitives/mds.rs
+++ b/halo2_gadgets/src/poseidon/primitives/mds.rs
@@ -81,7 +81,6 @@ pub(super) fn generate_mds<F: FromUniformBytes<64> + Ord, const T: usize>(
             if m == j {
                 acc
             } else {
-                let diff: F = x_j - *x_m;
                 // We can invert freely; by construction, the elements of xs are distinct.
                 acc * (x - x_m) * (x_j - x_m).invert().unwrap()
             }