diff --git a/CHANGELOG.md b/CHANGELOG.md
index e7ac968e..3fb54ead 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,7 +22,8 @@ All notable changes to this project will be documented in this file, in reverse
 
 ### Fixed
 
-- Nothing.
+- [#225](https://github.com/zendframework/zend-mail/pull/225) fixes duplicate `to` and `subject` headers on Windows reported in
+  [#22](https://github.com/zendframework/zend-mail/issues/22)
 
 ## 2.10.0 - 2018-06-07
 
diff --git a/src/Transport/Sendmail.php b/src/Transport/Sendmail.php
index 821c94e3..78aeb851 100644
--- a/src/Transport/Sendmail.php
+++ b/src/Transport/Sendmail.php
@@ -221,12 +221,7 @@ protected function prepareBody(Mail\Message $message)
      */
     protected function prepareHeaders(Mail\Message $message)
     {
-        // On Windows, simply return verbatim
-        if ($this->isWindowsOs()) {
-            return $message->getHeaders()->toString();
-        }
-
-        // On *nix platforms, strip the "to" header
+        // Strip the "to" and "subject" headers
         $headers = clone $message->getHeaders();
         $headers->removeHeader('To');
         $headers->removeHeader('Subject');
diff --git a/test/Transport/SendmailTest.php b/test/Transport/SendmailTest.php
index 9200863a..cb898c30 100644
--- a/test/Transport/SendmailTest.php
+++ b/test/Transport/SendmailTest.php
@@ -27,6 +27,7 @@ class SendmailTest extends TestCase
     public $message;
     public $additional_headers;
     public $additional_parameters;
+    public $operating_system;
 
     public function setUp()
     {
@@ -71,9 +72,14 @@ public function getMessage()
         return $message;
     }
 
+    public function isWindows()
+    {
+        return $this->operating_system === 'WIN';
+    }
+
     public function testReceivesMailArtifactsOnUnixSystems()
     {
-        if ($this->operating_system == 'WIN') {
+        if ($this->isWindows()) {
             $this->markTestSkipped('This test is *nix-specific');
         }
 
@@ -119,7 +125,7 @@ public function testReceivesMailArtifactsOnWindowsSystems()
 
     public function testLinesStartingWithFullStopsArePreparedProperlyForWindows()
     {
-        if ($this->operating_system != 'WIN') {
+        if (! $this->isWindows()) {
             $this->markTestSkipped('This test is Windows-specific');
         }
 
@@ -252,4 +258,33 @@ public function testDoNotAllowMessageWithoutToAndCcAndBccHeaders()
         $this->expectException(RuntimeException::class);
         $this->transport->send($message);
     }
+
+    /**
+     * @see https://github.com/zendframework/zend-mail/issues/22
+     */
+    public function testHeadersToAndSubjectAreNotDuplicated()
+    {
+        $lineBreak = $this->isWindows() ? "\r\n" : "\n";
+
+        $message = new Message();
+        $message
+            ->addTo('matthew@example.org')
+            ->addFrom('ralph@example.org')
+            ->setSubject('Greetings and Salutations!')
+            ->setBody("Sorry, I'm going to be late today!");
+
+        $this->transport->send($message);
+
+        $this->assertEquals('matthew@example.org', $this->to);
+        $this->assertEquals('Greetings and Salutations!', $this->subject);
+
+        $this->assertNotContains(
+            'To: matthew@example.org, matthew@example.org' . $lineBreak,
+            $this->additional_headers
+        );
+        $this->assertNotContains(
+            'Subject: Greetings and Salutations!, Greetings and Salutations!' . $lineBreak,
+            $this->additional_headers
+        );
+    }
 }