diff --git a/lib/functions.php b/lib/functions.php
index e649481..b1a4f58 100644
--- a/lib/functions.php
+++ b/lib/functions.php
@@ -102,8 +102,8 @@ function normalizeName(string $name): string
     if (isset($name[253]) || !\preg_match($pattern, $name)) {
         throw new InvalidNameException("Name '{$name}' is not a valid hostname.");
     }
-    if ($name[strlen($name)-1] === '.') {
-        $name = substr($name, 0, -1);
+    if ($name[\strlen($name)-1] === '.') {
+        $name = \substr($name, 0, -1);
     }
     return $name;
 }