diff --git a/pageserver/src/tenant.rs b/pageserver/src/tenant.rs
index f75a03a508..1a3016e7f1 100644
--- a/pageserver/src/tenant.rs
+++ b/pageserver/src/tenant.rs
@@ -3393,7 +3393,13 @@ impl TenantShard {
                 .collect_vec();
 
             for timeline in timelines {
-                timeline.maybe_freeze_ephemeral_layer().await;
+                // Include a span with the timeline ID. The parent span already has the tenant ID.
+                let span =
+                    info_span!("maybe_freeze_ephemeral_layer", timeline_id = %timeline.timeline_id);
+                timeline
+                    .maybe_freeze_ephemeral_layer()
+                    .instrument(span)
+                    .await;
             }
         }
 
diff --git a/pageserver/src/tenant/timeline.rs b/pageserver/src/tenant/timeline.rs
index fe622713e9..f2833674a9 100644
--- a/pageserver/src/tenant/timeline.rs
+++ b/pageserver/src/tenant/timeline.rs
@@ -1893,6 +1893,8 @@ impl Timeline {
     // an ephemeral layer open forever when idle.  It also freezes layers if the global limit on
     // ephemeral layer bytes has been breached.
     pub(super) async fn maybe_freeze_ephemeral_layer(&self) {
+        debug_assert_current_span_has_tenant_and_timeline_id();
+
         let Ok(mut write_guard) = self.write_lock.try_lock() else {
             // If the write lock is held, there is an active wal receiver: rolling open layers
             // is their responsibility while they hold this lock.