diff --git a/modules/openapi-generator/src/main/resources/typescript-fetch/modelOneOf.mustache b/modules/openapi-generator/src/main/resources/typescript-fetch/modelOneOf.mustache
index 37018c1172c0..0e65dec85ea9 100644
--- a/modules/openapi-generator/src/main/resources/typescript-fetch/modelOneOf.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-fetch/modelOneOf.mustache
@@ -24,7 +24,7 @@ export function {{classname}}FromJSONTyped(json: any, ignoreDiscriminator: boole
     switch (json['{{discriminator.propertyBaseName}}']) {
 {{#discriminator.mappedModels}}
         case '{{mappingName}}':
-            return Object.assign({}, {{modelName}}FromJSONTyped(json, true), { {{discriminator.propertyName}}: '{{mappingName}}' });
+            return Object.assign({}, {{modelName}}FromJSONTyped(json, true), { {{discriminator.propertyName}}: '{{mappingName}}' } as const);
 {{/discriminator.mappedModels}}
         default:
             throw new Error(`No variant of {{classname}} exists with '{{discriminator.propertyName}}=${json['{{discriminator.propertyName}}']}'`);