diff --git a/implementations/javascript/packages/schema/src/reflection.ts b/implementations/javascript/packages/schema/src/reflection.ts
index d8e5590..ad930d3 100644
--- a/implementations/javascript/packages/schema/src/reflection.ts
+++ b/implementations/javascript/packages/schema/src/reflection.ts
@@ -6,5 +6,5 @@ export interface SchemaDefinition {
     schema: Value,
     imports: Imports,
     definitionName: symbol,
-    variant: symbol | undefined,
+    variant?: symbol,
 }