diff --git a/scripts/update_iana_uri_schemes.py b/scripts/update_iana_uri_schemes.py
index aa8b58c5..4ba3e245 100644
--- a/scripts/update_iana_uri_schemes.py
+++ b/scripts/update_iana_uri_schemes.py
@@ -47,7 +47,7 @@ ignored_schemes_other = r"""
 %(other)s
 """
 
-ignored_schemes = "^(%%s%%s%%s%%s)$" %% (
+ignored_schemes = "^({}{}{}{})$".format(
     ignored_schemes_permanent,
     ignored_schemes_provisional,
     ignored_schemes_historical,