diff --git a/core/components/simplesearch/model/simplesearch/simplesearch.class.php b/core/components/simplesearch/model/simplesearch/simplesearch.class.php
index 7e63fc9..d9586f2 100644
--- a/core/components/simplesearch/model/simplesearch/simplesearch.class.php
+++ b/core/components/simplesearch/model/simplesearch/simplesearch.class.php
@@ -458,7 +458,7 @@ public function addHighlighting($string, $cls = 'simplesearch-highlight', $tag =
         $searchStrings = explode(' ', $this->searchString);
         foreach ($searchStrings as $searchString) {
             $quoteValue = preg_quote($searchString, '/');
-            $string     = preg_replace('/' . $quoteValue . '/i', '<'.$tag.' class="'.$cls.'">$0</'.$tag.'>', $string);
+            $string     = preg_replace('/' . $quoteValue . '/iu', '<'.$tag.' class="'.$cls.'">$0</'.$tag.'>', $string);
         }
 
         return $string;