diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3465e55..906c1fc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Fixed #296: multipart requests are not serialized on browser platform
 - Fixed #301: data is not decoded correctly when responseType is "json" (thanks antikalk)
+- Fixed #300: FormData object containing null or undefined value is not serialized correctly
 
 ## 2.4.0
 
diff --git a/test/e2e-specs.js b/test/e2e-specs.js
index 36f4c7c..c11b244 100644
--- a/test/e2e-specs.js
+++ b/test/e2e-specs.js
@@ -923,6 +923,29 @@ const tests = [
       });
     }
   },
+  {
+    description: 'should serialize FormData instance correctly when it contains null or undefined value #300',
+    expected: 'resolved: {"status":200, ...',
+    before: helpers.setMultipartSerializer,
+    func: function (resolve, reject) {
+      var ponyfills = cordova.plugin.http.ponyfills;
+      var formData = new ponyfills.FormData();
+      formData.append('myNullValue', null);
+      formData.append('myUndefinedValue', undefined);
+
+      var url = 'https://httpbin.org/anything';
+      var options = { method: 'post', data: formData };
+      cordova.plugin.http.sendRequest(url, options, resolve, reject);
+    },
+    validationFunc: function (driver, result) {
+      helpers.checkResult(result, 'resolved');
+      result.data.status.should.be.equal(200);
+      JSON.parse(result.data.data).form.should.be.eql({
+        myNullValue: 'null',
+        myUndefinedValue: 'undefined'
+      });
+    }
+  },
 
   // TODO: not ready yet
   // {
diff --git a/www/ponyfills.js b/www/ponyfills.js
index 67b9bbc..e49e6d7 100644
--- a/www/ponyfills.js
+++ b/www/ponyfills.js
@@ -18,7 +18,7 @@ module.exports = function init(global) {
       value.lastModifiedDate = new Date();
       value.name = filename || '';
     } else {
-      value = value.toString ? value.toString() : value;
+      value = String(value);
     }
 
     this.__items.push([ name, value ]);