diff --git a/lib/Application/Authentication/AuthenticatedUser.php b/lib/Application/Authentication/AuthenticatedUser.php
index e9829aa28..f2ebda388 100644
--- a/lib/Application/Authentication/AuthenticatedUser.php
+++ b/lib/Application/Authentication/AuthenticatedUser.php
@@ -168,6 +168,9 @@ public function Username()
 
     private function EnsureNull($value)
     {
+        if ($value === null) {
+            return null;
+        }
         $value = trim($value);
         if (empty($value)) {
             return null;