diff --git a/setup.cfg b/setup.cfg
index bbe000fadf..508cb0af7c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -124,7 +124,7 @@ distutils.setup_keywords =
 	dependency_links = setuptools.dist:assert_string_list
 	test_loader = setuptools.dist:check_importable
 	test_runner = setuptools.dist:check_importable
-	use_2to3 = setuptools.dist:invalid_ignored_if_false
+	use_2to3 = setuptools.dist:invalid_unless_false
 egg_info.writers =
 	PKG-INFO = setuptools.command.egg_info:write_pkg_info
 	requires.txt = setuptools.command.egg_info:write_requirements
diff --git a/setuptools/dist.py b/setuptools/dist.py
index 5f114d4c02..8e2111a52b 100644
--- a/setuptools/dist.py
+++ b/setuptools/dist.py
@@ -289,11 +289,11 @@ def assert_bool(dist, attr, value):
         raise DistutilsSetupError(tmpl.format(attr=attr, value=value))
 
 
-def invalid_ignored_if_false(dist, attr, value):
+def invalid_unless_false(dist, attr, value):
     if not value:
-        warnings.warn("{attr} is ignored", DistDeprecationWarning)
+        warnings.warn(f"{attr} is ignored.", DistDeprecationWarning)
         return
-    raise DistutilsSetupError(f"{attr} is invalid if it is set to a true value.")
+    raise DistutilsSetupError(f"{attr} is invalid.")
 
 
 def check_requirements(dist, attr, value):