diff --git a/app/code/Magento/Eav/Model/Entity/Attribute/Source/AbstractSource.php b/app/code/Magento/Eav/Model/Entity/Attribute/Source/AbstractSource.php
index 36ad026029056..a81d437acea36 100644
--- a/app/code/Magento/Eav/Model/Entity/Attribute/Source/AbstractSource.php
+++ b/app/code/Magento/Eav/Model/Entity/Attribute/Source/AbstractSource.php
@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+
 namespace Magento\Eav\Model\Entity\Attribute\Source;
 
 /**
@@ -65,7 +66,7 @@ public function getOptionText($value)
     {
         $options = $this->getAllOptions();
         // Fixed for tax_class_id and custom_design
-        if (sizeof($options) > 0) {
+        if (count($options) > 0) {
             foreach ($options as $option) {
                 if (isset($option['value']) && $option['value'] == $value) {
                     return isset($option['label']) ? $option['label'] : $option['value'];
@@ -88,7 +89,7 @@ public function getOptionText($value)
     public function getOptionId($value)
     {
         foreach ($this->getAllOptions() as $option) {
-            if (strcasecmp($option['label'], $value) == 0 || $option['value'] == $value) {
+            if ($this->mbStrcasecmp($option['label'], $value) == 0 || $option['value'] == $value) {
                 return $option['value'];
             }
         }
@@ -166,4 +167,20 @@ public function toOptionArray()
     {
         return $this->getAllOptions();
     }
+
+    /**
+     * Multibyte support strcasecmp function version.
+     *
+     * @param string $str1
+     * @param string $str2
+     * @return int
+     */
+    private function mbStrcasecmp($str1, $str2)
+    {
+        $encoding = mb_internal_encoding();
+        return strcmp(
+            mb_strtoupper($str1, $encoding),
+            mb_strtoupper($str2, $encoding)
+        );
+    }
 }