diff --git a/lib/Config/Hooks.php b/lib/Config/Hooks.php
index 47001e6c76..630754e651 100644
--- a/lib/Config/Hooks.php
+++ b/lib/Config/Hooks.php
@@ -4,6 +4,7 @@ namespace MailPoet\Config;
 
 use MailPoet\Models\Setting;
 use MailPoet\Subscription\Form;
+use MailPoet\WP\Functions as WPFunctions;
 
 class Hooks {
 
@@ -24,13 +25,15 @@ class Hooks {
 
   function setupSubscriptionEvents() {
     $subscribe = Setting::getValue('subscribe', array());
+    $wp = new WPFunctions;
+
     // Subscribe in comments
     if(
       isset($subscribe['on_comment']['enabled'])
       &&
       (bool)$subscribe['on_comment']['enabled']
     ) {
-      if(is_user_logged_in()) {
+      if($wp->isUserLoggedIn()) {
         add_action(
           'comment_form_field_comment',
           '\MailPoet\Subscription\Comment::extendLoggedInForm'
diff --git a/lib/Subscribers/ConfirmationEmailMailer.php b/lib/Subscribers/ConfirmationEmailMailer.php
index a20fe63b5b..80dbc6209d 100644
--- a/lib/Subscribers/ConfirmationEmailMailer.php
+++ b/lib/Subscribers/ConfirmationEmailMailer.php
@@ -7,6 +7,7 @@ use MailPoet\Models\Setting;
 use MailPoet\Models\Subscriber;
 use MailPoet\Subscription\Url;
 use MailPoet\Util\Helpers;
+use MailPoet\WP\Functions as WPFunctions;
 
 class ConfirmationEmailMailer {
 
@@ -15,13 +16,19 @@ class ConfirmationEmailMailer {
   /** @var Mailer */
   private $mailer;
 
+  /** @var WPFunctions */
+  private $wp;
+
   /**
    * @param Mailer|null $mailer
    */
-  function __construct($mailer = null) {
+  function __construct($mailer = null, WPFunctions $wp = null) {
     if($mailer) {
       $this->mailer = $mailer;
     }
+    if(!$wp) {
+      $this->wp = new WPFunctions;
+    }
   }
 
   function sendConfirmationEmail(Subscriber $subscriber) {
@@ -33,7 +40,7 @@ class ConfirmationEmailMailer {
 
     $subscriber->count_confirmations++;
     $subscriber->save();
-    if(!is_user_logged_in() && $subscriber->count_confirmations > self::MAX_CONFIRMATION_EMAILS) {
+    if(!$this->wp->isUserLoggedIn() && $subscriber->count_confirmations > self::MAX_CONFIRMATION_EMAILS) {
       return false;
     }
 
diff --git a/lib/Subscription/Throttling.php b/lib/Subscription/Throttling.php
index 269da4e38f..72acc063f8 100644
--- a/lib/Subscription/Throttling.php
+++ b/lib/Subscription/Throttling.php
@@ -4,6 +4,7 @@ namespace MailPoet\Subscription;
 use MailPoet\Models\SubscriberIP;
 use MailPoet\Util\Helpers;
 use MailPoet\WP\Hooks;
+use MailPoet\WP\Functions as WPFunctions;
 
 class Throttling {
   static function throttle() {
@@ -13,8 +14,9 @@ class Throttling {
     $subscription_limit_base = Hooks::applyFilters('mailpoet_subscription_limit_base', MINUTE_IN_SECONDS);
 
     $subscriber_ip = Helpers::getIP();
+    $wp = new WPFunctions;
 
-    if($subscription_limit_enabled && !is_user_logged_in()) {
+    if($subscription_limit_enabled && !$wp->isUserLoggedIn()) {
       if(!empty($subscriber_ip)) {
         $subscription_count = SubscriberIP::where('ip', $subscriber_ip)
           ->whereRaw(
diff --git a/lib/WP/Functions.php b/lib/WP/Functions.php
index 9a39ff27e1..340a85c504 100644
--- a/lib/WP/Functions.php
+++ b/lib/WP/Functions.php
@@ -32,6 +32,10 @@ class Functions {
     return call_user_func_array('home_url', func_get_args());
   }
 
+  function isUserLoggedIn() {
+    return call_user_func_array('is_user_logged_in', func_get_args());
+  }
+
   function getImageInfo($id) {
     /*
      * In some cases wp_get_attachment_image_src ignore the second parameter
diff --git a/tests/integration/Config/ShortcodesTest.php b/tests/integration/Config/ShortcodesTest.php
index 2ff571bbf7..eb00321716 100644
--- a/tests/integration/Config/ShortcodesTest.php
+++ b/tests/integration/Config/ShortcodesTest.php
@@ -11,6 +11,7 @@ use MailPoet\Models\Subscriber;
 use MailPoet\Newsletter\Url;
 use MailPoet\Router\Router;
 use MailPoet\Tasks\Sending as SendingTask;
+use MailPoet\WP\Functions as WPFunctions;
 
 class ShortcodesTest extends \MailPoetTest {
   function _before() {
@@ -56,7 +57,7 @@ class ShortcodesTest extends \MailPoetTest {
 
   function testItDisplaysManageSubscriptionFormForLoggedinExistingUsers() {
     $wp_user = wp_set_current_user(1);
-    expect(is_user_logged_in())->true();
+    expect((new WPFunctions)->isUserLoggedIn())->true();
     $subscriber = Subscriber::create();
     $subscriber->hydrate(Fixtures::get('subscriber_template'));
     $subscriber->email = $wp_user->data->user_email;
@@ -72,7 +73,7 @@ class ShortcodesTest extends \MailPoetTest {
 
   function testItDoesNotDisplayManageSubscriptionFormForLoggedinNonexistentSubscribers() {
     $wp_user = wp_set_current_user(1);
-    expect(is_user_logged_in())->true();
+    expect((new WPFunctions)->isUserLoggedIn())->true();
     expect(Subscriber::findOne($wp_user->data->user_email))->false();
 
     $shortcodes = new Shortcodes();
@@ -83,7 +84,7 @@ class ShortcodesTest extends \MailPoetTest {
 
   function testItDoesNotDisplayManageSubscriptionFormForLoggedOutUsers() {
     wp_set_current_user(0);
-    expect(is_user_logged_in())->false();
+    expect((new WPFunctions)->isUserLoggedIn())->false();
 
     $shortcodes = new Shortcodes();
     $shortcodes->init();
@@ -93,7 +94,7 @@ class ShortcodesTest extends \MailPoetTest {
 
   function testItDisplaysLinkToManageSubscriptionPageForLoggedinExistingUsers() {
     $wp_user = wp_set_current_user(1);
-    expect(is_user_logged_in())->true();
+    expect((new WPFunctions)->isUserLoggedIn())->true();
     $subscriber = Subscriber::create();
     $subscriber->hydrate(Fixtures::get('subscriber_template'));
     $subscriber->email = $wp_user->data->user_email;
@@ -108,7 +109,7 @@ class ShortcodesTest extends \MailPoetTest {
 
   function testItDoesNotDisplayLinkToManageSubscriptionPageForLoggedinNonexistentSubscribers() {
     $wp_user = wp_set_current_user(1);
-    expect(is_user_logged_in())->true();
+    expect((new WPFunctions)->isUserLoggedIn())->true();
     expect(Subscriber::findOne($wp_user->data->user_email))->false();
 
     $shortcodes = new Shortcodes();
@@ -119,7 +120,7 @@ class ShortcodesTest extends \MailPoetTest {
 
   function testItDoesNotDisplayManageSubscriptionPageForLoggedOutUsers() {
     wp_set_current_user(0);
-    expect(is_user_logged_in())->false();
+    expect((new WPFunctions)->isUserLoggedIn())->false();
 
     $shortcodes = new Shortcodes();
     $shortcodes->init();