diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index 9d93aa47337..b23937b5df1 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -282,6 +282,7 @@ pub fn serve<T: BeaconChainTypes>(
             }
         });
 
+    // Create a `warp` filter that rejects request whilst the node is syncing.
     let not_while_syncing_filter = warp::any()
         .and(network_globals.clone())
         .and(chain_filter.clone())
diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index 40b40160dfe..b570357b9db 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -19,7 +19,7 @@
 		* [/lighthouse](./api-lighthouse.md)
     		* [Validator Inclusion APIs](./validator-inclusion.md)
 	* [Validator Client API](./api-vc.md)
-    * [Prometheus Metrics](./advanced_metrics.md)
+	* [Prometheus Metrics](./advanced_metrics.md)
 * [Advanced Usage](./advanced.md)
     * [Database Configuration](./advanced_database.md)
 	* [Local Testnets](./local-testnets.md)
diff --git a/common/slot_clock/src/lib.rs b/common/slot_clock/src/lib.rs
index bf4fb6cda5b..0fe1bedfeda 100644
--- a/common/slot_clock/src/lib.rs
+++ b/common/slot_clock/src/lib.rs
@@ -25,7 +25,7 @@ pub trait SlotClock: Send + Sync + Sized {
     fn now(&self) -> Option<Slot>;
 
     /// Returns the slot at this present time if genesis has happened. Otherwise, returns the
-    /// genesis slot.
+    /// genesis slot. Returns `None` if there is an error reading the clock.
     fn now_or_genesis(&self) -> Option<Slot> {
         if self.is_prior_to_genesis()? {
             Some(self.genesis_slot())