diff --git a/main/Net/GenericUri.class.php b/main/Net/GenericUri.class.php
index 3f234ca030..95eaef8e1b 100644
--- a/main/Net/GenericUri.class.php
+++ b/main/Net/GenericUri.class.php
@@ -778,7 +778,7 @@ public function normalize($matched)
 			if (mb_strlen($char) == 1) {
 				if (
 					!preg_match(
-						'/^['.$this->unreservedPartChars.']$/',
+						'/^['.$this->unreservedPartChars.']$/u',
 						$char
 					)
 				)
@@ -786,7 +786,7 @@ public function normalize($matched)
 			} else {
 				if (
 					preg_match(
-						'/^['.GenericUri::CHARS_UNRESERVED.']$/',
+						'/^['.GenericUri::CHARS_UNRESERVED.']$/u',
 						rawurldecode($char)
 					)
 				)
@@ -797,4 +797,4 @@ public function normalize($matched)
 			return $char;
 		}
 	}
-?>
\ No newline at end of file
+?>