diff --git a/form.php b/form.php
index b5419d5..919d446 100644
--- a/form.php
+++ b/form.php
@@ -584,7 +584,7 @@ class form
   public function convertDate ($inputDate, $inputFormat, $outputFormat)
   // {{{
   {
-    $date = DateTime::CreateFromFormat ($inputFormat, $inputDate);
+    $date = \DateTime::CreateFromFormat ($inputFormat, $inputDate);
     if ($date === false)
       return $inputDate;
     $errors = $date->getLastErrors();