1 files changed, 9 insertions, 2 deletions
diff --git a/sphinx/builders/htmlhelp.py b/sphinx/builders/htmlhelp.py
index ec86740e1..9ba7ae9b0 100644
--- a/sphinx/builders/htmlhelp.py
+++ b/sphinx/builders/htmlhelp.py
@@ -22,13 +22,14 @@ from sphinx.config import string_classes
 from sphinx.environment.adapters.indexentries import IndexEntries
 from sphinx.locale import __
 from sphinx.util import logging
-from sphinx.util.osutil import make_filename
+from sphinx.util.osutil import make_filename_from_project
 from sphinx.util.pycompat import htmlescape
 
 if False:
     # For type annotation
     from typing import Any, Dict, IO, List, Tuple  # NOQA
     from sphinx.application import Sphinx  # NOQA
+    from sphinx.config import Config  # NOQA
     from sphinx.util.typing import unicode  # NOQA
 
 
@@ -337,12 +338,18 @@ class HTMLHelpBuilder(StandaloneHTMLBuilder):
             f.write('</UL>\n')
 
 
+def default_htmlhelp_basename(config):
+    # type: (Config) -> unicode
+    """Better default htmlhelp_basename setting."""
+    return make_filename_from_project(config.project) + 'doc'
+
+
 def setup(app):
     # type: (Sphinx) -> Dict[unicode, Any]
     app.setup_extension('sphinx.builders.html')
     app.add_builder(HTMLHelpBuilder)
 
-    app.add_config_value('htmlhelp_basename', lambda self: make_filename(self.project), None)
+    app.add_config_value('htmlhelp_basename', default_htmlhelp_basename, None)
     app.add_config_value('htmlhelp_file_suffix', None, 'html', string_classes)
     app.add_config_value('htmlhelp_link_suffix', None, 'html', string_classes)