diff --git a/src/nsfns.m b/src/nsfns.m
index ba363629686..c8a41f5b4b0 100644
--- a/src/nsfns.m
+++ b/src/nsfns.m
@@ -1476,13 +1476,8 @@ Turn the input menu (an NSMenu) into a lisp list for tracking on lisp side
 DEFUN ("ns-frame-list-z-order", Fns_frame_list_z_order,
        Sns_frame_list_z_order, 0, 1, 0,
        doc: /* Return list of Emacs' frames, in Z (stacking) order.
-The optional argument TERMINAL specifies which display to ask about.
-TERMINAL should be either a frame or a display name (a string).  If
-omitted or nil, that stands for the selected frame's display.  Return
-nil if TERMINAL contains no Emacs frame.
-
-As a special case, if TERMINAL is non-nil and specifies a live frame,
-return the child frames of that frame in Z (stacking) order.
+If TERMINAL is non-nil and specifies a live frame, return the child
+frames of that frame in Z (stacking) order.
 
 Frames are listed from topmost (first) to bottommost (last).  */)
   (Lisp_Object terminal)
@@ -1492,8 +1487,6 @@ Frames are listed from topmost (first) to bottommost (last).  */)
 
   if (FRAMEP (terminal) && FRAME_LIVE_P (XFRAME (terminal)))
     parent = [FRAME_NS_VIEW (XFRAME (terminal)) window];
-  else if (!NILP (terminal))
-    return Qnil;
 
   for (NSWindow *win in [[NSApp orderedWindows] reverseObjectEnumerator])
     {