From a164895431f361a994258910bac36d4cfc6ef83f Mon Sep 17 00:00:00 2001
From: Lucas Haug <lucas.haug@ausy-technologies.de>
Date: Fri, 16 Sep 2022 18:58:41 +0200
Subject: [PATCH] Aims to fix #1342

---
 src/TransformOperationExecutor.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/TransformOperationExecutor.ts b/src/TransformOperationExecutor.ts
index 0533f03df..ac5ad84f4 100644
--- a/src/TransformOperationExecutor.ts
+++ b/src/TransformOperationExecutor.ts
@@ -294,7 +294,7 @@ export class TransformOperationExecutor {
         //     throw new Error(`Cannot determine type for ${(targetType as any).name }.${propertyName}, did you forget to specify a @Type?`);
 
         // if newValue is a source object that has method that match newKeyName then skip it
-        if (newValue.constructor.prototype) {
+        if (newValue.constructor.prototype && !(newValue instanceof Map)) {
           const descriptor = Object.getOwnPropertyDescriptor(newValue.constructor.prototype, newValueKey);
           if (
             (this.transformationType === TransformationType.PLAIN_TO_CLASS ||