diff --git a/examples/plugins/letsencrypt_example_plugins.py b/examples/plugins/letsencrypt_example_plugins.py
index a364ae905..2810d0d40 100644
--- a/examples/plugins/letsencrypt_example_plugins.py
+++ b/examples/plugins/letsencrypt_example_plugins.py
@@ -20,7 +20,7 @@ class Authenticator(common.Plugin):
     # "self" as first argument, e.g. def prepare(self)...
 
 
-class Installer(common.Plugins):
+class Installer(common.Plugin):
     """Example Installer."""
     zope.interface.implements(interfaces.IInstaller)
     zope.interface.classProvides(interfaces.IPluginFactory)