diff --git a/pageserver/src/tenant/timeline/detach_ancestor.rs b/pageserver/src/tenant/timeline/detach_ancestor.rs
index f5831a5d8a..1fb5618f6b 100644
--- a/pageserver/src/tenant/timeline/detach_ancestor.rs
+++ b/pageserver/src/tenant/timeline/detach_ancestor.rs
@@ -265,7 +265,7 @@ pub(super) async fn prepare(
             // we are safe to inspect the latest uploaded, because we can only witness this after
             // restart is complete and ancestor is no more.
             let latest = accessor.latest_uploaded_index_part();
-            if !latest.lineage.is_detached_from_original_ancestor() {
+            if !latest.lineage.is_detached_from_ancestor() {
                 return Err(NoAncestor);
             }
         }