diff --git a/rdmo/projects/views/project.py b/rdmo/projects/views/project.py
index 20b2cec753..88fc5fc99a 100644
--- a/rdmo/projects/views/project.py
+++ b/rdmo/projects/views/project.py
@@ -109,7 +109,7 @@ def get(self, request, token):
                 error = _('Sorry, your invitation has been expired.')
                 invite.delete()
             elif invite.user and invite.user != request.user:
-                error = _('Sorry, but this invitation is for the user "{}".'.format(invite.user))
+                error = _('Sorry, but this invitation is for the user "%s".') % invite.user
             elif Membership.objects.filter(project=invite.project, user=request.user).exists():
                 invite.delete()
                 return redirect(invite.project.get_absolute_url())