diff --git a/addons/l10n_id_efaktur/models/efaktur.py b/addons/l10n_id_efaktur/models/efaktur.py
index b54c8382fc76eb2ae26e058f0a5c7844b350e9f7..71a9b5ea8b422013b7eeecb4c479cd1b3631fbe1 100644
--- a/addons/l10n_id_efaktur/models/efaktur.py
+++ b/addons/l10n_id_efaktur/models/efaktur.py
@@ -98,12 +98,14 @@ class Efaktur(models.Model):
 
     @api.onchange('min')
     def _onchange_min(self):
-        self.min = '%013d' % int(re.sub(r'\D', '', self.min))
+        min_val = re.sub(r'\D', '', str(self.min)) or 0
+        self.min = '%013d' % int(min_val)
         if not self.max or int(self.min) > int(self.max):
             self.max = self.min
 
     @api.onchange('max')
     def _onchange_max(self):
-        self.max = '%013d' % int(re.sub(r'\D', '', self.max))
+        max_val = re.sub(r'\D', '', str(self.max)) or 0
+        self.max = '%013d' % int(max_val)
         if not self.min or int(self.min) > int(self.max):
             self.min = self.max