diff --git a/test/yargs-parser.js b/test/yargs-parser.js
index 5b59c615..5fabd6f7 100644
--- a/test/yargs-parser.js
+++ b/test/yargs-parser.js
@@ -2375,4 +2375,31 @@ describe('yargs-parser', function () {
     })
     argv.a.should.deep.equal(['a.txt', 'b.txt'])
   })
+
+  // Patching for https://snyk.io/vuln/SNYK-JS-YARGSPARSER-560381
+  it('should not pollute the prototype', function () {
+    const argv = parser(['--foo', 'bar'], {
+      alias: {
+        z: 'zoom'
+      },
+      default: {
+        settings: jsonPath
+      },
+      config: 'settings'
+    })
+
+    argv.should.have.property('herp', 'derp')
+    argv.should.have.property('zoom', 55)
+    argv.should.have.property('foo').and.deep.equal('bar')
+
+    expect({}.bbb).to.equal(undefined)
+    expect({}.aaa).to.equal(undefined)
+  })
+
+  it('should not pollute the prototype', function () {
+    parser(['-f.__proto__.foo', '99', '-x.y.__proto__.bar', '100', '--__proto__', '200'])
+    Object.keys({}.__proto__).length.should.equal(0) // eslint-disable-line
+    expect({}.foo).to.equal(undefined)
+    expect({}.bar).to.equal(undefined)
+  })
 })