diff --git a/crates/bevy_hierarchy/src/lib.rs b/crates/bevy_hierarchy/src/lib.rs
index 0959fa8130a7b..f156086b1a926 100644
--- a/crates/bevy_hierarchy/src/lib.rs
+++ b/crates/bevy_hierarchy/src/lib.rs
@@ -41,6 +41,7 @@ impl Plugin for HierarchyPlugin {
     fn build(&self, app: &mut App) {
         app.register_type::<Children>()
             .register_type::<Parent>()
+            .register_type::<smallvec::SmallVec<[bevy_ecs::entity::Entity; 8]>>()
             .add_event::<HierarchyEvent>();
     }
 }