diff --git a/src/middlewares/parsers/schema.preprocessor.ts b/src/middlewares/parsers/schema.preprocessor.ts
index 81c6ee21..5792f9aa 100644
--- a/src/middlewares/parsers/schema.preprocessor.ts
+++ b/src/middlewares/parsers/schema.preprocessor.ts
@@ -59,6 +59,7 @@ if (!Array.prototype['flatMap']) {
   Array.prototype['flatMap'] = function (lambda) {
     return Array.prototype.concat.apply([], this.map(lambda));
   };
+  Object.defineProperty(Array.prototype, 'flatMap', { enumerable: false });
 }
 const httpMethods = new Set([
   'get',