diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 6df8c3912a3..42b9600a0ac 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,7 @@
+2013-08-13  Xue Fuqiao  <xfq.free@gmail.com>
+
+	* positions.texi (Word Motion): Remove redundant sentence.
+
 2013-08-13  Glenn Morris  <rgm@gnu.org>
 
 	* lists.texi (List Elements):
diff --git a/doc/lispref/positions.texi b/doc/lispref/positions.texi
index 119ad98a53d..5cb1a851a5b 100644
--- a/doc/lispref/positions.texi
+++ b/doc/lispref/positions.texi
@@ -191,8 +191,8 @@ whether a given character is part of a word.  @xref{Syntax Tables}.
 
 @deffn Command forward-word &optional count
 This function moves point forward @var{count} words (or backward if
-@var{count} is negative).  If @var{count} is @code{nil}, it moves
-forward one word.
+@var{count} is negative).  If @var{count} is omitted or @code{nil}, it
+defaults to 1.
 
 ``Moving one word'' means moving until point crosses a
 word-constituent character and then encounters a word-separator
@@ -210,7 +210,7 @@ If @code{inhibit-field-text-motion} is non-@code{nil},
 this function ignores field boundaries.
 
 In an interactive call, @var{count} is specified by the numeric prefix
-argument.  If @var{count} is omitted or @code{nil}, it defaults to 1.
+argument.
 @end deffn
 
 @deffn Command backward-word &optional count
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index ff9f4ff8707..0c8791d8af7 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2013-08-13  Xue Fuqiao  <xfq.free@gmail.com>
+
+	* simple.el (backward-word): Mention the optional argument.
+
 2013-08-13  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* frameset.el (frameset--make): Rename constructor from make-frameset.
diff --git a/lisp/simple.el b/lisp/simple.el
index 0edf5ca8d9c..6825c41becc 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -3338,6 +3338,7 @@ extract characters that are special to a buffer, and should not
 be copied into other buffers."
   (funcall filter-buffer-substring-function beg end delete))
 
+;; FIXME: `with-wrapper-hook' is obsolete
 (defun buffer-substring--filter (beg end &optional delete)
   (with-wrapper-hook filter-buffer-substring-functions (beg end delete)
     (cond
@@ -5670,7 +5671,8 @@ current object."
 
 (defun backward-word (&optional arg)
   "Move backward until encountering the beginning of a word.
-With argument ARG, do this that many times."
+With argument ARG, do this that many times.
+If ARG is omitted or nil, move point backward one word."
   (interactive "^p")
   (forward-word (- (or arg 1))))
 
diff --git a/src/ChangeLog b/src/ChangeLog
index 7c6f9c3557f..28e8ab66e37 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2013-08-13  Xue Fuqiao  <xfq.free@gmail.com>
+
+	* syntax.c (forward_word):
+	* cmds.c (forward_char, backward_char): Mention the optional argument.
+
 2013-08-13  Dmitry Antipov  <dmantipov@yandex.ru>
 
 	* window.h (struct window): Convert left_fringe_width
diff --git a/src/cmds.c b/src/cmds.c
index 3ebad50184a..ce91877f85e 100644
--- a/src/cmds.c
+++ b/src/cmds.c
@@ -86,6 +86,7 @@ DEFUN ("forward-char", Fforward_char, Sforward_char, 0, 1, "^p",
        doc: /* Move point N characters forward (backward if N is negative).
 On reaching end or beginning of buffer, stop and signal error.
 Interactively, N is the numeric prefix argument.
+If N is omitted or nil, move point 1 character forward.
 
 Depending on the bidirectional context, the movement may be to the
 right or to the left on the screen.  This is in contrast with
@@ -99,6 +100,7 @@ DEFUN ("backward-char", Fbackward_char, Sbackward_char, 0, 1, "^p",
        doc: /* Move point N characters backward (forward if N is negative).
 On attempt to pass beginning or end of buffer, stop and signal error.
 Interactively, N is the numeric prefix argument.
+If N is omitted or nil, move point 1 character backward.
 
 Depending on the bidirectional context, the movement may be to the
 right or to the left on the screen.  This is in contrast with
diff --git a/src/syntax.c b/src/syntax.c
index 6d52d115889..f5b37303a4a 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -1464,6 +1464,7 @@ scan_words (register ptrdiff_t from, register EMACS_INT count)
 
 DEFUN ("forward-word", Fforward_word, Sforward_word, 0, 1, "^p",
        doc: /* Move point forward ARG words (backward if ARG is negative).
+If ARG is omitted or nil, move point forward one word.
 Normally returns t.
 If an edge of the buffer or a field boundary is reached, point is left there
 and the function returns nil.  Field boundaries are not noticed if