diff --git a/plugins/Referrers/Columns/Keyword.php b/plugins/Referrers/Columns/Keyword.php
index 48e8a9efd481609385c30fb1e6f7bb5a0b025587..b3bfc374b1c0ee5198d0a3227f15af807b908552 100644
--- a/plugins/Referrers/Columns/Keyword.php
+++ b/plugins/Referrers/Columns/Keyword.php
@@ -8,6 +8,7 @@
  */
 namespace Piwik\Plugins\Referrers\Columns;
 
+use Piwik\Common;
 use Piwik\Piwik;
 use Piwik\Plugins\Referrers\Segment;
 use Piwik\Tracker\Request;
@@ -44,11 +45,7 @@ class Keyword extends Base
         $information = $this->getReferrerInformationFromRequest($request);
 
         if (!empty($information['referer_keyword'])) {
-            if (function_exists('mb_substr')) {
-                return mb_substr($information['referer_keyword'], 0, 255, 'UTF-8');
-            } else {  
-                return substr($information['referer_keyword'], 0, 255);
-            }
+            return Common::mb_substr($information['referer_keyword'], 0, 255);
         }
 
         return $information['referer_keyword'];
diff --git a/plugins/Referrers/Columns/ReferrerName.php b/plugins/Referrers/Columns/ReferrerName.php
index 9f3d122bdf805cc5e748dd1205620bc5ffc9ec89..ded0a48f9e8907d87c2aaa1bf433700f0dfee3fb 100644
--- a/plugins/Referrers/Columns/ReferrerName.php
+++ b/plugins/Referrers/Columns/ReferrerName.php
@@ -8,6 +8,7 @@
  */
 namespace Piwik\Plugins\Referrers\Columns;
 
+use Piwik\Common;
 use Piwik\Plugins\Referrers\Segment;
 use Piwik\Tracker\Request;
 use Piwik\Tracker\Visitor;
@@ -38,11 +39,7 @@ class ReferrerName extends Base
         $information = $this->getReferrerInformationFromRequest($request);
 
         if (!empty($information['referer_name'])) {
-            if (function_exists('mb_substr')) {
-                return mb_substr($information['referer_name'], 0, 70, 'UTF-8');
-            } else {
-                return substr($information['referer_name'], 0, 70);
-            }
+            return Common::mb_substr($information['referer_name'], 0, 70);
         }
         return $information['referer_name'];
     }