diff --git a/src/hash/merkle_proofs.rs b/src/hash/merkle_proofs.rs
index 20654fa2..ad269699 100644
--- a/src/hash/merkle_proofs.rs
+++ b/src/hash/merkle_proofs.rs
@@ -72,7 +72,7 @@ impl<F: Extendable<D>, const D: usize> CircuitBuilder<F, D> {
             state = HashOutTarget::from_vec(outputs[0..4].to_vec());
         }
 
-        let index = self.le_sum(leaf_index_bits[proof.siblings.len()..].to_vec().into_iter());
+        let index = self.le_sum(leaf_index_bits[proof.siblings.len()..].iter().copied());
 
         for i in 0..4 {
             self.random_access(
diff --git a/src/lib.rs b/src/lib.rs
index f1014b73..26209c58 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,7 @@
 #![allow(clippy::type_complexity)]
 #![allow(clippy::len_without_is_empty)]
 #![allow(clippy::needless_range_loop)]
+#![allow(clippy::return_self_not_must_use)]
 #![feature(asm_sym)]
 #![feature(generic_const_exprs)]
 #![feature(specialization)]