diff --git a/lib/Subscription/CaptchaSession.php b/lib/Subscription/CaptchaSession.php
index d2c9e363fc..8fe12de1f1 100644
--- a/lib/Subscription/CaptchaSession.php
+++ b/lib/Subscription/CaptchaSession.php
@@ -48,9 +48,10 @@ class CaptchaSession {
   }
 
   private function getKey($type) {
-    if ($this->session->getId() === null) {
+    $session_id = $this->session->getId();
+    if ($session_id === null) {
       throw new \Exception("MailPoet session not initialized.");
     }
-    return implode('_', ['MAILPOET', $this->session->getId(), $type]);
+    return implode('_', ['MAILPOET', $session_id, $type]);
   }
 }
diff --git a/tests/integration/Subscription/CaptchaSessionTest.php b/tests/integration/Subscription/CaptchaSessionTest.php
new file mode 100644
index 0000000000..f7e5d2490f
--- /dev/null
+++ b/tests/integration/Subscription/CaptchaSessionTest.php
@@ -0,0 +1,78 @@
+<?php
+namespace MailPoet\Test\Subscription;
+
+use MailPoet\Config\Session;
+use MailPoet\Subscription\CaptchaSession;
+use MailPoet\Util\Cookies;
+use MailPoet\WP\Functions as WPFunctions;
+use PHPUnit_Framework_MockObject_MockObject as MockObject;
+
+class CaptchaSessionTest extends \MailPoetTest {
+
+  /** @var CaptchaSession */
+  private $captcha_session;
+
+  /** @var MockObject */
+  private $cookies_mock;
+
+  function _before() {
+    $this->cookies_mock = $this->createMock(Cookies::class);
+    $this->captcha_session = new CaptchaSession(new WPFunctions, new Session($this->cookies_mock));
+  }
+
+  function testIsAvailableWhenCookieExists() {
+    $this->cookies_mock
+      ->method('get')
+      ->willReturn('abcd');
+    expect($this->captcha_session->isAvailable())->true();
+  }
+
+  function testIsNotAvailableWhenCookieDoesntExits() {
+    $this->cookies_mock
+      ->method('get')
+      ->willReturn(null);
+    expect($this->captcha_session->isAvailable())->false();
+  }
+
+  function testItCanStoreAndRetrieveFormData() {
+    $this->cookies_mock
+      ->method('get')
+      ->willReturn('abcd');
+    $form_data = ['email' => 'email@example.com'];
+    $this->captcha_session->setFormData($form_data);
+    expect($this->captcha_session->getFormData())->equals($form_data);
+  }
+
+  function testItCanStoreAndRetrieveCaptchaHash() {
+    $this->cookies_mock
+      ->method('get')
+      ->willReturn('abcd');
+    $hash = '1234';
+    $this->captcha_session->setCaptchaHash($hash);
+    expect($this->captcha_session->getCaptchaHash())->equals($hash);
+  }
+
+  function testItCanResetSessionData() {
+    $this->cookies_mock
+      ->method('get')
+      ->willReturn('abcd');
+    $this->captcha_session->setFormData(['email' => 'email@example.com']);
+    $this->captcha_session->setCaptchaHash('hash123');
+    $this->captcha_session->reset();
+    expect($this->captcha_session->getFormData())->false();
+    expect($this->captcha_session->getCaptchaHash())->false();
+  }
+
+  function testItAssociatesDataWithSession() {
+    $session1 = 'abcd';
+    $session2 = 'efgh';
+    $this->cookies_mock
+      ->method('get')
+      ->willReturnOnConsecutiveCalls($session1, $session1, $session2, $session1);
+    $hash = '1234';
+    $this->captcha_session->setCaptchaHash($hash);
+    expect($this->captcha_session->getCaptchaHash())->equals($hash);
+    expect($this->captcha_session->getCaptchaHash())->false();
+    expect($this->captcha_session->getCaptchaHash())->equals($hash);
+  }
+}