diff --git a/wagtail/contrib/redirects/models.py b/wagtail/contrib/redirects/models.py
index 94e1f31ba8..15003892a6 100644
--- a/wagtail/contrib/redirects/models.py
+++ b/wagtail/contrib/redirects/models.py
@@ -150,6 +150,7 @@ class Redirect(models.Model):
 
         return path
 
+    @staticmethod
     def normalise_page_route_path(url):
         # Strip whitespace
         url = url.strip()