1 files changed, 3 insertions, 1 deletions

diff --git a/src/editfns.c b/src/editfns.c
index 3b2876f01e8..3c2a858b46e 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -4479,7 +4479,9 @@ functions if all the text being accessed has this property.  */);
                doc: /* The user's name, based upon the real uid only.  */);
 
   DEFVAR_LISP ("operating-system-release", Voperating_system_release,
-               doc: /* The operating system kernel version Emacs is running on.  */);
+               doc: /* The kernel version of the operating system on which Emacs is running.
+The value is a string.  It can also be nil if Emacs doesn't
+know how to get the kernel version on the underlying OS.  */);
 
   DEFVAR_BOOL ("binary-as-unsigned",
                binary_as_unsigned,