diff --git a/pep-0433.txt b/pep-0433.txt
index 413fd65c1..6aee32ad9 100644
--- a/pep-0433.txt
+++ b/pep-0433.txt
@@ -647,8 +647,9 @@ On Linux older than 2.6.23, ``O_CLOEXEC`` flag is simply ignored. So
 we have to check that the flag is supported by calling ``fcntl()``. If
 it does not work, we have to set the flag using ``fcntl()``.
 
-XXX what is the behaviour on Linux older than 2.6.27
-XXX with SOCK_CLOEXEC? XXX
+On Linux older than 2.6.27, if the ``SOCK_CLOEXEC`` flag is set in the
+socket type, ``socket()`` or ``socketpair()`` fail and ``errno`` is set
+to ``EINVAL``.
 
 New functions:
 
@@ -657,7 +658,7 @@ New functions:
  * ``accept4()``: available on Linux 2.6.28+ (and glibc 2.10)
 
 If ``accept4()`` is called on Linux older than 2.6.28, ``accept4()``
-returns ``-1`` (fail) and errno is set to ``ENOSYS``.
+returns ``-1`` (fail) and ``errno`` is set to ``ENOSYS``.
 
 
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