diff --git a/src/middlewares/parsers/req.parameter.mutator.ts b/src/middlewares/parsers/req.parameter.mutator.ts
index c4b3b8d3..d56aa787 100644
--- a/src/middlewares/parsers/req.parameter.mutator.ts
+++ b/src/middlewares/parsers/req.parameter.mutator.ts
@@ -254,6 +254,7 @@ export class RequestParameterMutator {
      */
     const field = REQUEST_FIELDS[$in];
     if (req[field]?.[name]) {
+      if (Array.isArray(req[field][name])) return;
       const value = req[field][name].split(delimiter);
       req[field][name] = value;
     }