diff --git a/pageserver/src/tenant/storage_layer.rs b/pageserver/src/tenant/storage_layer.rs
index 6426f46196..89d851b05d 100644
--- a/pageserver/src/tenant/storage_layer.rs
+++ b/pageserver/src/tenant/storage_layer.rs
@@ -433,6 +433,8 @@ impl LayerFringe {
         let entry = self.layers.entry(layer_id.clone());
         match entry {
             Entry::Occupied(mut entry) => {
+                // On this branch, we don't add to planned_reads_by_lsn
+                // even though we might be interested in a different lsn_range.
                 entry.get_mut().target_keyspace.add_keyspace(keyspace);
             }
             Entry::Vacant(entry) => {