diff --git a/crates/chain/src/chain_data.rs b/crates/chain/src/chain_data.rs
index 5615b094..aa1e74d4 100644
--- a/crates/chain/src/chain_data.rs
+++ b/crates/chain/src/chain_data.rs
@@ -271,6 +271,8 @@ impl<A: BlockAnchor> FullTxOut<ObservedAs<A>> {
 
     /// Whether the utxo is/was/will be spendable with chain `tip`.
     ///
+    /// Currently this method does not take into account the locktime.
+    ///
     /// This is the alternative version of [`is_spendable_at`] which depends on `chain_position`
     /// being a [`ObservedAs<A>`] where `A` implements [`BlockAnchor`].
     ///
@@ -286,7 +288,6 @@ impl<A: BlockAnchor> FullTxOut<ObservedAs<A>> {
                     return false;
                 }
             }
-            // [TODO] Why are unconfirmed txs always considered unspendable here?
             ObservedAs::Unconfirmed(_) => return false,
         };
 
diff --git a/crates/chain/src/indexed_tx_graph.rs b/crates/chain/src/indexed_tx_graph.rs
index dac05e72..2de8114a 100644
--- a/crates/chain/src/indexed_tx_graph.rs
+++ b/crates/chain/src/indexed_tx_graph.rs
@@ -55,10 +55,11 @@ impl<A: BlockAnchor, IA: Append> Append for IndexedAdditions<A, IA> {
         self.graph_additions.append(other.graph_additions);
         self.index_additions.append(other.index_additions);
         if self.last_height < other.last_height {
-            let last_height = other
-                .last_height
-                .expect("must exist as it is larger than self.last_height");
-            self.last_height.replace(last_height);
+            self.last_height = Some(
+                other
+                    .last_height
+                    .expect("must exist as it is larger than self.last_height"),
+            );
         }
     }
 }