diff --git a/man2/mkdir.2 b/man2/mkdir.2
index 41fad5578..42fc26b73 100644
--- a/man2/mkdir.2
+++ b/man2/mkdir.2
@@ -54,7 +54,8 @@ The argument
 specifies the permissions to use.
 It is modified by the process's
 .I umask
-in the usual way: the permissions of the created directory are
+in the usual way: in the absence of a default acl, the permissions of the
+created directory are
 .RI ( mode " & ~" umask " & 0777)."
 Other mode bits of the created directory depend on the operating system.
 For Linux, see below.
@@ -212,8 +213,6 @@ POSIX.1-2008.
 Under Linux, apart from the permission bits, only the
 .B S_ISVTX
 mode bit is honored.
-That is, under Linux the created directory actually gets mode
-.RI ( mode " & ~" umask " & 01777)."
 See also
 .BR stat (2).
 .PP
diff --git a/man2/mknod.2 b/man2/mknod.2
index e93c3454a..7a8dd1e1f 100644
--- a/man2/mknod.2
+++ b/man2/mknod.2
@@ -63,8 +63,9 @@ listed below and the permissions for the new node.
 
 The permissions are modified by the process's
 .I umask
-in the usual way: the permissions of the created node are
-.IR "(mode & ~umask)" .
+in the usual way: in the absence of a default acl, the permissions of the
+created node are
+.RI ( mode " & ~" umask ).
 
 The file type must be one of
 .BR S_IFREG ,
diff --git a/man2/open.2 b/man2/open.2
index 053bab10f..1d22b58c2 100644
--- a/man2/open.2
+++ b/man2/open.2
@@ -275,7 +275,8 @@ is ignored.
 The effective permissions are modified by
 the process's
 .I umask
-in the usual way: The permissions of the created file are
+in the usual way: In the absence of a default acl, the permissions of the
+created file are
 .IR "(mode\ &\ ~umask)" .
 Note that this mode applies only to future accesses of the
 newly created file; the
diff --git a/man2/umask.2 b/man2/umask.2
index e5e57506a..905f2cdc2 100644
--- a/man2/umask.2
+++ b/man2/umask.2
@@ -63,6 +63,17 @@ argument to
 and
 .BR mkdir (2).
 
+Alternatively, if the parent directory has a default acl (see
+.BR acl (5)),
+the umask is ignored, the default acl is inherited, the permission bits are set
+based on the inherited acl, and permission bits absent in the
+.I mode
+argument are turned off.  For example, the default acl
+u::rwx,g::r-x,o::r-x is equivalent to a umask of 022, and with a
+.I mode
+argument of 0666 (rw-rw-rw-), the resulting file permissions are 0644
+(rw-r--r--).
+
 The constants that should be used to specify
 .I mask
 are described under