diff --git a/lib/legacy/legacy-data-mixin.html b/lib/legacy/legacy-data-mixin.html
index 21124629ca..eef8802a57 100644
--- a/lib/legacy/legacy-data-mixin.html
+++ b/lib/legacy/legacy-data-mixin.html
@@ -19,6 +19,9 @@
     constructor(message) {
       super(message);
       this.name = this.constructor.name;
+      // Affordances for ensuring instanceof works after babel ES5 compilation
+      this.constructor = UndefinedArgumentError;
+      this.__proto__ = UndefinedArgumentError.prototype;
     }
   };