diff --git a/js/model/ParticleAtom.ts b/js/model/ParticleAtom.ts
index 844eb46..30629d0 100644
--- a/js/model/ParticleAtom.ts
+++ b/js/model/ParticleAtom.ts
@@ -108,12 +108,16 @@ class ParticleAtom extends PhetioObject {
     this.protons = createObservableArray( {
       // tandem: options.tandem.createTandem( 'protons' ),
       phetioType: createObservableArray.ObservableArrayIO( Particle.ParticleIO ),
-      hasListenerOrderDependencies: true // TODO: Not positive that this is true, but CT will let us know, see https://github.com/phetsims/build-a-nucleus/issues/105
+      lengthPropertyOptions: {
+        hasListenerOrderDependencies: true // needed in BAN, see https://github.com/phetsims/build-a-nucleus/issues/105
+      }
     } );
     this.neutrons = createObservableArray( {
       // tandem: options.tandem.createTandem( 'neutrons' ),
       phetioType: createObservableArray.ObservableArrayIO( Particle.ParticleIO ),
-      hasListenerOrderDependencies: true // TODO: Not positive that this is true, but CT will let us know, see https://github.com/phetsims/build-a-nucleus/issues/105
+      lengthPropertyOptions: {
+        hasListenerOrderDependencies: true // needed in BAN, see https://github.com/phetsims/build-a-nucleus/issues/105
+      }
     } );
     this.electrons = createObservableArray( {
       // tandem: options.tandem.createTandem( 'electrons' ),