diff --git a/doc/conf.py b/doc/conf.py
index 8f7734d76a0d72d4cdc98055351156360a61c525..fd9baec94912b5b182c9eb8f0e9754048186992c 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -71,7 +71,7 @@ master_doc = "index"
 project = "clapper"
 package = distribution(project)
 
-copyright = "%s, Idiap Research Institute" % time.strftime("%Y")  # noqa: A001
+copyright = f"{time.strftime('%Y')}, Idiap Research Institute"  # noqa: A001
 
 # The short X.Y version.
 version = package.version
diff --git a/src/clapper/click.py b/src/clapper/click.py
index b9351385a62abcdfa204086c49544aab3f3b44fe..38084a2edbbdb2575d466345082c982ae55282df 100644
--- a/src/clapper/click.py
+++ b/src/clapper/click.py
@@ -486,7 +486,7 @@ class AliasedGroup(click.Group):
         if len(matches) == 1:
             return click.Group.get_command(self, ctx, matches[0])
 
-        ctx.fail("Too many matches: %s" % ", ".join(sorted(matches)))  # noqa: RET503
+        ctx.fail(f"Too many matches: {', '.join(sorted(matches))}")  # noqa: RET503
 
 
 def user_defaults_group(