diff --git a/crates/blockchain-tree/src/blockchain_tree.rs b/crates/blockchain-tree/src/blockchain_tree.rs
index 7f58c2a0b..bd1d72c97 100644
--- a/crates/blockchain-tree/src/blockchain_tree.rs
+++ b/crates/blockchain-tree/src/blockchain_tree.rs
@@ -298,7 +298,7 @@ impl<DB: Database, EF: ExecutorFactory> BlockchainTree<DB, EF> {
 
         let parent = block.parent_num_hash();
 
-        // check if block parent can be found in Tree
+        // check if block parent can be found in any side chain.
         if let Some(chain_id) = self.block_indices().get_blocks_chain_id(&parent.hash) {
             // found parent in side tree, try to insert there
             return self.try_insert_block_into_side_chain(block, chain_id, block_validation_kind)
@@ -917,6 +917,7 @@ impl<DB: Database, EF: ExecutorFactory> BlockchainTree<DB, EF> {
         // If block is already canonical don't return error.
         if let Some(header) = self.find_canonical_header(block_hash)? {
             info!(target: "blockchain_tree", ?block_hash, "Block is already canonical, ignoring.");
+            // TODO: this could be fetched from the chainspec first
             let td = self.externals.database().provider()?.header_td(block_hash)?.ok_or(
                 CanonicalError::from(BlockValidationError::MissingTotalDifficulty {
                     hash: *block_hash,
diff --git a/crates/consensus/beacon/src/engine/mod.rs b/crates/consensus/beacon/src/engine/mod.rs
index 641376824..54e98eb8a 100644
--- a/crates/consensus/beacon/src/engine/mod.rs
+++ b/crates/consensus/beacon/src/engine/mod.rs
@@ -632,8 +632,9 @@ where
             return Ok(OnForkChoiceUpdated::invalid_state())
         }
 
+        // check if the new head hash is connected to any ancestor that we previously marked as
+        // invalid
         let lowest_buffered_ancestor_fcu = self.lowest_buffered_ancestor_or(state.head_block_hash);
-
         if let Some(status) = self.check_invalid_ancestor(lowest_buffered_ancestor_fcu) {
             return Ok(OnForkChoiceUpdated::with_invalid(status))
         }
@@ -659,6 +660,7 @@ where
         let start = Instant::now();
         let make_canonical_result = self.blockchain.make_canonical(&state.head_block_hash);
         let elapsed = self.record_make_canonical_latency(start, &make_canonical_result);
+
         let status = match make_canonical_result {
             Ok(outcome) => {
                 match outcome {