diff --git a/www/index.php b/www/index.php
index bf85018..4449267 100644
--- a/www/index.php
+++ b/www/index.php
@@ -434,7 +434,9 @@
 			$_SESSION['_config']['errmsg'] .= _("First and/or last names were blank.")."<br>\n";
 		}
 		if($_SESSION['signup']['year'] < 1900 || $_SESSION['signup']['month'] < 1 || $_SESSION['signup']['month'] > 12 ||
-			$_SESSION['signup']['day'] < 1 || $_SESSION['signup']['day'] > 31)
+			$_SESSION['signup']['day'] < 1 || $_SESSION['signup']['day'] > 31 ||
+			!checkdate($_SESSION['signup']['month'],$_SESSION['signup']['day'],$_SESSION['signup']['year']) ||
+			mktime(0,0,0,$_SESSION['signup']['month'],$_SESSION['signup']['day'],$_SESSION['signup']['year']) > time() )
 		{
 			$id = 1;
 			$_SESSION['_config']['errmsg'] .= _("Invalid date of birth")."<br>\n";