note that fork and forkpty raise OSError on failure
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index f76cd97..98d0cf9 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -1631,7 +1631,8 @@
.. function:: fork()
Fork a child process. Return ``0`` in the child and the child's process id in the
- parent. Availability: Macintosh, Unix.
+ parent. If an error occurs :exc:`OSError` is raised.
+ Availability: Macintosh, Unix.
.. function:: forkpty()
@@ -1640,7 +1641,8 @@
terminal. Return a pair of ``(pid, fd)``, where *pid* is ``0`` in the child, the
new child's process id in the parent, and *fd* is the file descriptor of the
master end of the pseudo-terminal. For a more portable approach, use the
- :mod:`pty` module. Availability: Macintosh, some flavors of Unix.
+ :mod:`pty` module. If an error occurs :exc:`OSError` is raised.
+ Availability: Macintosh, some flavors of Unix.
.. function:: kill(pid, sig)