diff --git a/wp-register.php b/wp-register.php
index 8591de7b74..b3e556b2d6 100644
--- a/wp-register.php
+++ b/wp-register.php
@@ -30,6 +30,11 @@ case 'register':
   if ( username_exists( $user_login ) )
 		$errors['user_login'] = __('<strong>ERROR</strong>: This username is already registered, please choose another one.');
 
+	/* checking the email isn't already used by another user */
+	$email_exists = $wpdb->get_row("SELECT user_email FROM $wpdb->users WHERE user_email = '$user_email'");
+	if ( $email_exists)
+		die (__('<strong>ERROR</strong>: This email address is already registered, please supply another.'));
+
 	if ( 0 == count($errors) ) {
 		$password = substr( md5( uniqid( microtime() ) ), 0, 7);