diff --git a/src/TraitExpression.ts b/src/TraitExpression.ts
index ade1782..2490377 100644
--- a/src/TraitExpression.ts
+++ b/src/TraitExpression.ts
@@ -74,8 +74,9 @@ export class TraitExpression<
 }
 
 export namespace TraitExpression {
+    declare const nullSuperclassSymbol: unique symbol
     export class NullSuperclass {
-        static readonly _tag = "@thilawyn/traitify-ts/TraitExpression.NullSuperclass"
+        static readonly [nullSuperclassSymbol]: true
         constructor(...args: any[]) {}
     }