diff --git a/packages/app-backend/src/clone.js b/packages/app-backend/src/clone.js
index 6e35a4434..9da8e3941 100644
--- a/packages/app-backend/src/clone.js
+++ b/packages/app-backend/src/clone.js
@@ -376,7 +376,7 @@ function clone (object, options) {
     // if the object cannot / should not be cloned, don't
     if (
       // promise-like
-      typeof object.then === 'function' ||
+      (hasOwnProperty.call(object, 'then') && typeof object.then === 'function') ||
       // errors
       object instanceof Error ||
       // weakmaps