diff --git a/crates/chain/src/indexer/keychain_txout.rs b/crates/chain/src/indexer/keychain_txout.rs
index 7973a0254e..1b5c6a478b 100644
--- a/crates/chain/src/indexer/keychain_txout.rs
+++ b/crates/chain/src/indexer/keychain_txout.rs
@@ -540,7 +540,8 @@ impl<K: Clone + Ord + Debug> KeychainTxOutIndex<K> {
     pub fn lookahead_to_target(&mut self, keychain: K, target_index: u32) -> ChangeSet {
         let mut changeset = ChangeSet::default();
         if let Some((next_index, _)) = self.next_index(keychain.clone()) {
-            let temp_lookahead = (target_index + 1)
+            let temp_lookahead = target_index
+                .saturating_add(1)
                 .checked_sub(next_index)
                 .filter(|&index| index > 0);