diff --git a/register.php b/register.php
index 095b6cc..200a9ae 100644
--- a/register.php
+++ b/register.php
@@ -29,7 +29,7 @@
 		if ($_SERVER['REQUEST_METHOD'] == "POST") {
 			if (!empty($_POST['username'])) {
 				if (preg_match($username_re, $_POST['username']) === 1) {
-					if (preg_match('/^' . $username . ':x:\d+:\d+:[\w\d\s,@()]*:[\w\d\s\/]*:[\d\s\w\/]*/m', file_get_contents('/sshfs/etc/passwd')) !== 1) {
+					if (!file_exists('/vm/' . $_POST['username'])) {
 						if (!file_exists("/var/tmp/register/" . sanitize($_POST['username'])))
 							$username = sanitize($_POST['username']);
 						else $username_err = "A request for the username " . $_POST['username'] . " exists already. Try again later or choose a different username.";
@@ -64,7 +64,7 @@
 			}
 
 			if (!empty($_POST['ssh'])) {
-				$ret = shell_exec("bash -c 'ssh-keygen -lf - <<< " . escapeshellarg($_POST['ssh']) . " &> /dev/null ; printf %d $?'");
+				$ret = shell_exec("bash -c \"ssh-keygen -lf - <<< " . escapeshellarg($_POST['ssh']) . " &> /dev/null ; printf %d $?\"");
 				if ($ret == 0) {
 					$ssh = $_POST['ssh'];
 				} else {