diff --git a/e107_handlers/login.php b/e107_handlers/login.php
index b40b89a80..f9b838656 100644
--- a/e107_handlers/login.php
+++ b/e107_handlers/login.php
@@ -278,7 +278,13 @@ class userlogin
 			{	// 'New user' probationary period expired - we can take them out of the class
 				$this->userData['user_class'] = $this->e107->user_class->ucRemove(e_UC_NEWUSER, $this->userData['user_class']);
 //				$this->e107->admin_log->e_log_event(4,__FILE__."|".__FUNCTION__."@".__LINE__,"DBG","Login new user complete",$this->userData['user_class'],FALSE,FALSE);
-				$sql->update('user',"`user_class` = '".$this->userData['user_class']."'", 'WHERE `user_id`='.$this->userData['user_id']. " LIMIT 1");
+
+				/**
+				 * issue e107inc/e107#3657: Third argument of update() function is for debugging purposes and NOT used for the WHERE clause.
+				 * Therefore the query was run without WHERE, which resulted into applyiing the new classes to all users....
+				 */
+				//$sql->update('user',"`user_class` = '".$this->userData['user_class']."'", 'WHERE `user_id`='.$this->userData['user_id']. " LIMIT 1");
+				$sql->update('user',"`user_class` = '" . $this->userData['user_class'] . "' WHERE `user_id`=" . $this->userData['user_id'] . " LIMIT 1");
 				unset($class_list[e_UC_NEWUSER]);
 				$edata_li = array('user_id' => $user_id, 'user_name' => $username, 'class_list' => implode(',',$class_list), 'user_email'=> $user_email);
 				$e_event->trigger('userNotNew', $edata_li);