diff --git a/src/decorated-merger.ts b/src/decorated-merger.ts
index 47b7277..8730c46 100644
--- a/src/decorated-merger.ts
+++ b/src/decorated-merger.ts
@@ -70,12 +70,11 @@ export const merger = <T extends any, Y extends any>(
   }
   const allProperties = getAllPropertiesToMerge(merge, options)
   for (const property of allProperties) {
-    const typeNew = typeof merge
-    if (typeNew === 'undefined' || typeNew === 'function') {
-      continue
-    }
     const oldValue = into[property.name]
     const newValue = merge[property.name]
+    if (newValue === undefined) {
+      continue
+    }
     if (oldValue === undefined) {
       into[property.name] = newValue
       continue
diff --git a/test/merge.test.ts b/test/merge.test.ts
index 03bf03c..e6ec35b 100644
--- a/test/merge.test.ts
+++ b/test/merge.test.ts
@@ -90,6 +90,15 @@ describe('Merging', () => {
     expect(newMovie.to).toBeDefined()
   })
 
+  it('Undefinded in new object should not override', () => {
+    let movieA = { title: 'test', genre: ['Drama'] }
+    const movieB = { title: undefined, genre: undefined }
+    const newMovie = merger(movieB, movieA)
+
+    expect(newMovie.title).toEqual('test')
+    expect(newMovie.genre[0]).toEqual('Drama')
+  })
+
   it('Two simple class with exsiting array should merge', () => {
     const car = getTestCar()
     const carNew = getTestCar()