diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 8e6642e9fcb..b1e5a7f365f 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -519,6 +519,7 @@ def _default_mime_types():
         '.html'   : 'text/html',
         '.htm'    : 'text/html',
         '.md'     : 'text/markdown',
+        '.markdown': 'text/markdown',
         '.txt'    : 'text/plain',
         '.bat'    : 'text/plain',
         '.c'      : 'text/plain',