diff --git a/doc/source/install.rst b/doc/source/install.rst
index b298d46..6b9b182 100644
--- a/doc/source/install.rst
+++ b/doc/source/install.rst
@@ -74,6 +74,10 @@ TMPDIR
     temporary directory. This defaults to the system-wide ``$TMPDIR``, or to ``/tmp/`` if not ``TMPDIR`` is
     not set. Choose it wisely, keeping in mind that in this directory a lot of cache files will be stored, and
     could therefore require hundreds of MB.
+UMASK
+    Umask affects created files permissions. This is important if you want to pass files to a MPD instance
+    that is running with a different users. There is no default umask, so that you can apply umask via your
+    standard system tools.
 
 Events
 ^^^^^^^^^