diff --git a/src/GlossifyBase.php b/src/GlossifyBase.php
index 0885247..5b2e6b8 100644
--- a/src/GlossifyBase.php
+++ b/src/GlossifyBase.php
@@ -44,7 +44,7 @@ abstract class GlossifyBase extends FilterBase {
       $term_norm = preg_replace('#/#', '\/', $term_norm);
       $pattern_parts[] = preg_replace('/ /', '\\s+', $term_norm);
     }
-    $pattern  = '/\b(' . implode('|', $pattern_parts) . ')\b/';
+    $pattern  = '/\b(' . implode('|', $pattern_parts) . ')\b/u';
     if (!$case_sensitivity) {
       $pattern .= 'i';
     }