Fix last change in lispref/display.texi.

Fixes: debbugs:15375

1 files changed, 1 insertions, 1 deletions

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 2e7d4f4c010..d63f98c55c4 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -4219,7 +4219,7 @@ This function returns the width of the left and right margins of
 @var{window} as a cons cell of the form @w{@code{(@var{left}
 . @var{right})}}.  If one of the two marginal areas does not exist,
 its width is returned as @code{nil}; if none of the two margins exist,
-the function returns @code{nil}.  If @var{window} is @code{nil}, the
+the function returns @code{(nil)}.  If @var{window} is @code{nil}, the
 selected window is used.
 @end defun