2 files changed, 12 insertions, 9 deletions
diff --git a/lisp/emacs-lisp/shortdoc.el b/lisp/emacs-lisp/shortdoc.el
index 7bb7d233b47..eb57e706608 100644
--- a/lisp/emacs-lisp/shortdoc.el
+++ b/lisp/emacs-lisp/shortdoc.el
@@ -145,7 +145,7 @@ There can be any number of :example/:result elements."
    :eval (substring "foobar" 3))
   (string-limit
    :eval (string-limit "foobar" 3)
-   :eval (string-limit "foobar" -3)
+   :eval (string-limit "foobar" 3 t)
    :eval (string-limit "foobar" 10))
   (split-string
    :eval (split-string "foo bar")
diff --git a/lisp/emacs-lisp/subr-x.el b/lisp/emacs-lisp/subr-x.el
index 6f4f7ed5dce..b79482fd4b3 100644
--- a/lisp/emacs-lisp/subr-x.el
+++ b/lisp/emacs-lisp/subr-x.el
@@ -286,17 +286,20 @@ result will have lines that are longer than LENGTH."
       (fill-region (point-min) (point-max)))
     (buffer-string)))
 
-(defun string-limit (string length)
+(defun string-limit (string length &optional end)
   "Return (up to) a LENGTH substring of STRING.
 If STRING is shorter than or equal to LENGTH, the entire string
-is returned unchanged.  If STRING is longer than LENGTH, and
-LENGTH is a positive number, return a substring consisting of the
-first LENGTH characters of STRING.  If LENGTH is negative, return
-a substring consisting of the last LENGTH characters of STRING."
+is returned unchanged.
+
+If STRING is longer than LENGTH, return a substring consisting of
+the first LENGTH characters of STRING.  If END is non-nil, return
+the last LENTGH characters instead."
+  (unless (natnump length)
+    (signal 'wrong-type-argument (list 'natnump length)))
   (cond
-   ((<= (length string) (abs length)) string)
-   ((>= length 0) (substring string 0 length))
-   ((substring string length))))
+   ((<= (length string) length) string)
+   (end (substring string (- (length string) length)))
+   (t (substring string 0 length))))
 
 (defun string-lines (string &optional omit-nulls)
   "Split STRING into a list of lines.