diff --git a/client/modules/vitis/forms/users/users_vitis_users.json b/client/modules/vitis/forms/users/users_vitis_users.json
index 822ecc7037eafea3f0ce2bde04516c06446f3c24..5ffc8a2d303395a5551060fb4a15a087be5d70a6 100644
--- a/client/modules/vitis/forms/users/users_vitis_users.json
+++ b/client/modules/vitis/forms/users/users_vitis_users.json
@@ -503,6 +503,7 @@
                         "name":"login",
                         "label":"FORM_LOGIN_USERS_USER",
                         "required":true,
+                        "pattern":"^[^@]+$",
                         "nb_cols":12
                     }
                 ]