diff --git a/src/QUI/ERP/Discount/Discount.php b/src/QUI/ERP/Discount/Discount.php
index 73cf0dc161fcb1aa9047a24f78359631ae756819..f7199d2eb3fb15394f19aae861bd8f7fb9074a62 100644
--- a/src/QUI/ERP/Discount/Discount.php
+++ b/src/QUI/ERP/Discount/Discount.php
@@ -57,7 +57,7 @@ public function __construct($id, Handler $Factory)
 
         // cleanup user group save
         $cleanup = QUI\Utils\ArrayHelper::cleanup($this->getAttribute('user_groups'));
-        $cleanup = implode(',', $cleanup);
+        $cleanup = \implode(',', $cleanup);
 
         if (!empty($cleanup)) {
             $cleanup = ','.$cleanup.',';
@@ -68,7 +68,7 @@ public function __construct($id, Handler $Factory)
 
         // cleanup product(s)
         $cleanup = QUI\Utils\ArrayHelper::cleanup($this->getAttribute('articles'));
-        $cleanup = implode(',', $cleanup);
+        $cleanup = \implode(',', $cleanup);
 
         if (!empty($cleanup)) {
             $cleanup = ','.$cleanup.',';
@@ -79,7 +79,7 @@ public function __construct($id, Handler $Factory)
 
         // cleanup user group save
         $cleanup = QUI\Utils\ArrayHelper::cleanup($this->getAttribute('user_groups'));
-        $cleanup = implode(',', $cleanup);
+        $cleanup = \implode(',', $cleanup);
 
         if (!empty($cleanup)) {
             $cleanup = ','.$cleanup.',';
@@ -90,7 +90,7 @@ public function __construct($id, Handler $Factory)
 
         // cleanup product(s)
         $cleanup = QUI\Utils\ArrayHelper::cleanup($this->getAttribute('articles'));
-        $cleanup = implode(',', $cleanup);
+        $cleanup = \implode(',', $cleanup);
 
         if (!empty($cleanup)) {
             $cleanup = ','.$cleanup.',';
@@ -264,9 +264,9 @@ public function canCombinedWith(Discount $Discount)
             return false;
         }
 
-        $combine = implode($combine, ',');
+        $combine = \implode($combine, ',');
 
-        if (!is_array($combine)) {
+        if (!\is_array($combine)) {
             return false;
         }
 
@@ -294,13 +294,13 @@ public function canUsedBy(QUI\Interfaces\Users\User $User)
         // usage definitions / limits
         $dateFrom  = $this->getAttribute('date_from');
         $dateUntil = $this->getAttribute('date_until');
-        $now       = time();
+        $now       = \time();
 
-        if ($dateFrom && strtotime($dateFrom) > $now) {
+        if ($dateFrom && \strtotime($dateFrom) > $now) {
             return false;
         }
 
-        if ($dateUntil && strtotime($dateUntil) < $now) {
+        if ($dateUntil && \strtotime($dateUntil) < $now) {
             return false;
         }
 
@@ -367,12 +367,12 @@ public function canUsedWith(QUI\ERP\Products\Interfaces\ProductInterface $Produc
         $articles   = $this->getAttribute('articles');
         $categories = $this->getAttribute('categories');
 
-        if (is_string($articles)) {
-            $articles = explode(',', $articles);
+        if (\is_string($articles)) {
+            $articles = \explode(',', $articles);
         }
 
-        if (is_string($categories)) {
-            $categories = explode(',', $categories);
+        if (\is_string($categories)) {
+            $categories = \explode(',', $categories);
         }
 
 
@@ -392,7 +392,7 @@ public function canUsedWith(QUI\ERP\Products\Interfaces\ProductInterface $Produc
         if (empty($categories)) {
             return true;
         }
-        
+
         foreach ($categories as $category) {
             $productCategories = $Product->getCategories();
 
diff --git a/src/QUI/ERP/Discount/EventHandling.php b/src/QUI/ERP/Discount/EventHandling.php
index fda602eadf375404bf9a28db00cee44b1f555e92..14fd306a09875ccff819dd6290f95dc5a9738a02 100644
--- a/src/QUI/ERP/Discount/EventHandling.php
+++ b/src/QUI/ERP/Discount/EventHandling.php
@@ -35,7 +35,7 @@ class EventHandling
      */
     protected static function getHandler()
     {
-        if (is_null(self::$Handler)) {
+        if (self::$Handler === null) {
             self::$Handler = new Handler();
         }
 
@@ -140,11 +140,11 @@ public static function onQuiqqerProductsCalcListProduct(
     ) {
         $userDiscounts = self::getUserDiscounts($Calc->getUser());
 
-        if (!is_array($userDiscounts)) {
+        if (!\is_array($userDiscounts) || empty($userDiscounts)) {
             return;
         }
 
-        $userDiscounts = array_filter($userDiscounts, function ($Discount) {
+        $userDiscounts = \array_filter($userDiscounts, function ($Discount) {
             /* @var $Discount Discount */
 
             // don't use manuel usage type
@@ -155,7 +155,7 @@ public static function onQuiqqerProductsCalcListProduct(
             return $Discount->getAttribute('scope') == Handler::DISCOUNT_SCOPE_EVERY_PRODUCT;
         });
 
-        if (!is_array($userDiscounts)) {
+        if (!\is_array($userDiscounts) || empty($userDiscounts)) {
             return;
         }
 
@@ -206,11 +206,11 @@ public static function onQuiqqerProductsCalcList(
     ) {
         $userDiscounts = self::getUserDiscounts($Calc->getUser());
 
-        if (!is_array($userDiscounts)) {
+        if (!\is_array($userDiscounts)) {
             return;
         }
 
-        $userDiscounts = array_filter($userDiscounts, function ($Discount) {
+        $userDiscounts = \array_filter($userDiscounts, function ($Discount) {
             /* @var $Discount Discount */
 
             // don't use manuel usage type
@@ -221,7 +221,7 @@ public static function onQuiqqerProductsCalcList(
             return $Discount->getAttribute('scope') == Handler::DISCOUNT_SCOPE_TOTAL;
         });
 
-        if (!is_array($userDiscounts)) {
+        if (!\is_array($userDiscounts)) {
             return;
         }
 
@@ -242,7 +242,7 @@ public static function onQuiqqerProductsCalcList(
             $productIds = $Discount->getAttribute('articles');
 
             if ($productIds) {
-                $productIds = explode(',', $productIds);
+                $productIds = \explode(',', $productIds);
 
                 // product id check
                 $existProductIdInList = function ($products, $productIds) {
@@ -267,7 +267,7 @@ public static function onQuiqqerProductsCalcList(
             $categories = $Discount->getAttribute('categories');
 
             if ($categories) {
-                $categories = explode(',', $categories);
+                $categories = \explode(',', $categories);
 
                 // product category check
                 $existCategoryInList = function ($products, $categories) {
diff --git a/src/QUI/ERP/Discount/Utils.php b/src/QUI/ERP/Discount/Utils.php
index 311e3bc6fcfaafa85d62ddaf4f4069be83c753ff..28b3893a3fc7fa6dc17b19db852ec9bea71ac671 100644
--- a/src/QUI/ERP/Discount/Utils.php
+++ b/src/QUI/ERP/Discount/Utils.php
@@ -26,7 +26,7 @@ class Utils
     public static function getUserDiscounts(UserInterface $User)
     {
         $guString = UserGroups::getUserGroupStringFromUser($User);
-        $guString = ','.str_replace(',', ',|,', $guString).',';
+        $guString = ','.\str_replace(',', ',|,', $guString).',';
 
         $result    = [];
         $Discounts = new Handler();
@@ -48,11 +48,11 @@ public static function getUserDiscounts(UserInterface $User)
 
 
         if (!empty($personalDiscounts)) {
-            $result = array_merge($personalDiscounts, $result);
+            $result = \array_merge($personalDiscounts, $result);
         }
 
         if (!empty($discounts)) {
-            $result = array_merge($discounts, $result);
+            $result = \array_merge($discounts, $result);
         }
 
         return $result;
@@ -86,11 +86,11 @@ public static function getProductDiscounts(Product $Product)
 
 
         if (!empty($productDiscounts)) {
-            $result = array_merge($productDiscounts, $result);
+            $result = \array_merge($productDiscounts, $result);
         }
 
         if (!empty($discounts)) {
-            $result = array_merge($discounts, $result);
+            $result = \array_merge($discounts, $result);
         }
 
         return $result;
@@ -105,7 +105,7 @@ public static function getProductDiscounts(Product $Product)
     public static function getActiveUserDiscounts(UserInterface $User)
     {
         $guString = UserGroups::getUserGroupStringFromUser($User);
-        $guString = ','.str_replace(',', ',|,', $guString).',';
+        $guString = ','.\str_replace(',', ',|,', $guString).',';
 
         $result    = [];
         $Discounts = new Handler();
@@ -129,11 +129,11 @@ public static function getActiveUserDiscounts(UserInterface $User)
 
 
         if (!empty($personalDiscounts)) {
-            $result = array_merge($personalDiscounts, $result);
+            $result = \array_merge($personalDiscounts, $result);
         }
 
         if (!empty($discounts)) {
-            $result = array_merge($discounts, $result);
+            $result = \array_merge($discounts, $result);
         }
 
         return $result;