diff --git a/certbot-nginx/certbot_nginx/_internal/nginxparser.py b/certbot-nginx/certbot_nginx/_internal/nginxparser.py
index 858fbc91c..b94b04d61 100644
--- a/certbot-nginx/certbot_nginx/_internal/nginxparser.py
+++ b/certbot-nginx/certbot_nginx/_internal/nginxparser.py
@@ -131,14 +131,14 @@ def load(_file):
 
 
 def dumps(blocks):
-    # type: (UnspacedList) -> six.text_type
+    # type: (UnspacedList) -> str
     """Dump to a Unicode string.
 
     :param UnspacedList block: The parsed tree
-    :rtype: six.text_type
+    :rtype: str
 
     """
-    return six.text_type(RawNginxDumper(blocks.spaced))
+    return str(RawNginxDumper(blocks.spaced))
 
 
 def dump(blocks, _file):
diff --git a/certbot/certbot/util.py b/certbot/certbot/util.py
index a87afe079..42c6af5ec 100644
--- a/certbot/certbot/util.py
+++ b/certbot/certbot/util.py
@@ -579,7 +579,7 @@ def is_wildcard_domain(domain):
 
     """
     wildcard_marker = b"*."  # type: Union[Text, bytes]
-    if isinstance(domain, six.text_type):
+    if isinstance(domain, str):
         wildcard_marker = u"*."
     return domain.startswith(wildcard_marker)