diff --git a/src/authentic2_auth_fedict/fields.py b/src/authentic2_auth_fedict/fields.py
index a3547b5..84f8b46 100644
--- a/src/authentic2_auth_fedict/fields.py
+++ b/src/authentic2_auth_fedict/fields.py
@@ -88,7 +88,7 @@ class StreetWidget(forms.TextInput):
             street_url = settings.IMIO_STREETS_URL
         else:
             passerelle_url = list(settings.KNOWN_SERVICES['passerelle'].values())[0]['url']
-            street_url = '%s/imio-liege-lisrue/lisrue-be/voies/' % passerelle_url
+            street_url = urljoin(passerelle_url, '/imio-liege-lisrue/lisrue-be/voies/')
         attrs['data-autocomplete-url'] = street_url
         super(forms.TextInput, self).__init__(attrs=attrs)