diff --git a/src/MD_STD.php b/src/MD_STD.php
index 723f07f..5293da4 100644
--- a/src/MD_STD.php
+++ b/src/MD_STD.php
@@ -944,7 +944,7 @@ final class MD_STD {
             return -1 * intval(str_replace("-", "", ltrim($date, "0-")));
         }
 
-        return intval(date("Ymd", strtotime($date)));
+        return intval(date("Ymd", self::strtotime($date)));
 
     }