diff --git a/lib/Alchemy/Phrasea/Model/Manipulator/UserManipulator.php b/lib/Alchemy/Phrasea/Model/Manipulator/UserManipulator.php
index 8104c04c47..3d0815370e 100644
--- a/lib/Alchemy/Phrasea/Model/Manipulator/UserManipulator.php
+++ b/lib/Alchemy/Phrasea/Model/Manipulator/UserManipulator.php
@@ -368,7 +368,7 @@ class UserManipulator implements ManipulatorInterface
             throw new InvalidArgumentException(sprintf('Email %s is not legal.', $email));
         }
 
-        if (null !== $this->repository->findByEmail($email)) {
+        if (($email !== null) && (null !== $this->repository->findByEmail($email))) {
             throw new RuntimeException(sprintf('User with email %s already exists.', $email));
         }