diff --git a/docs/configuration.rst b/docs/configuration.rst
index ae650009..0752b9c9 100644
--- a/docs/configuration.rst
+++ b/docs/configuration.rst
@@ -154,6 +154,7 @@ Description
       depending on the local operating system
     * ``"unix"``: ``"/"``
     * ``"windows"``: ``"\\\\|/<>:\"?*"``
+    * ``"ascii"``: ``"^0-9A-Za-z_."``
 
     Note: In a string with 2 or more characters, ``[]^-\`` need to be
     escaped with backslashes, e.g. ``"\\[\\]"``
diff --git a/gallery_dl/util.py b/gallery_dl/util.py
index 1733e093..ab8645b5 100644
--- a/gallery_dl/util.py
+++ b/gallery_dl/util.py
@@ -730,6 +730,7 @@ class PathFormat():
         "auto"   : "\\\\|/<>:\"?*" if WINDOWS else "/",
         "unix"   : "/",
         "windows": "\\\\|/<>:\"?*",
+        "ascii"  : "^0-9A-Za-z_.",
     }
 
     def __init__(self, extractor):