diff --git a/js/src/lib/firestore-particles.ts b/js/src/lib/firestore-particles.ts
index 940e557..368c025 100644
--- a/js/src/lib/firestore-particles.ts
+++ b/js/src/lib/firestore-particles.ts
@@ -130,7 +130,6 @@ export async function createParticle<T extends ParticleType>(
     properties,
     created_at: new Date(),
     created_by_email: createdByEmail,
-    updated_at: null,
   });
   const ref = await addDoc(typedCollection(collectionPath), particle);
   return ref.id;