diff --git a/addons/l10n_ch/wizard/dta_wizard.py b/addons/l10n_ch/wizard/dta_wizard.py
index 53bd0d94405..4a0a8582a0a 100755
--- a/addons/l10n_ch/wizard/dta_wizard.py
+++ b/addons/l10n_ch/wizard/dta_wizard.py
@@ -529,7 +529,7 @@ def _create_dta(obj, cr, uid, data, context):
                 if not v['reference'] \
                     or (mod10r(v['reference'][:-1]) != v['reference'] and \
                     not len(v['reference']) == 15):
-                raise wizard.except_wizard(_('Error'), _('You must provide ' \
+                    raise wizard.except_wizard(_('Error'), _('You must provide ' \
                         'a valid BVR reference number \n' \
                         'for the line: %s') % pline.name)
             if not v['partner_bvr']: