diff --git a/src/auto/configure b/src/auto/configure
index 347db65..70a06b4 100755
--- a/src/auto/configure
+++ b/src/auto/configure
Binary files differ
diff --git a/src/buffer.c b/src/buffer.c
index 4da9d63..050760f 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -512,12 +512,11 @@
  * buf_freeall() - free all things allocated for a buffer that are related to
  * the file.
  */
-/*ARGSUSED*/
     void
 buf_freeall(buf, del_buf, wipe_buf)
     buf_T	*buf;
-    int		del_buf;	/* buffer is going to be deleted */
-    int		wipe_buf;	/* buffer is going to be wiped out */
+    int		del_buf UNUSED;	    /* buffer is going to be deleted */
+    int		wipe_buf UNUSED;    /* buffer is going to be wiped out */
 {
 #ifdef FEAT_AUTOCMD
     int		is_curbuf = (buf == curbuf);
@@ -2437,11 +2436,10 @@
  * another tab page.
  * Returns NULL when there isn't any info.
  */
-/*ARGSUSED*/
     static wininfo_T *
 find_wininfo(buf, skip_diff_buffer)
     buf_T	*buf;
-    int		skip_diff_buffer;
+    int		skip_diff_buffer UNUSED;
 {
     wininfo_T	*wip;
 
@@ -4278,10 +4276,9 @@
  * Make "ffname" a full file name, set "sfname" to "ffname" if not NULL.
  * "ffname" becomes a pointer to allocated memory (or NULL).
  */
-/*ARGSUSED*/
     void
 fname_expand(buf, ffname, sfname)
-    buf_T	*buf;
+    buf_T	*buf UNUSED;
     char_u	**ffname;
     char_u	**sfname;
 {
@@ -5577,11 +5574,10 @@
  * this buffer.  Call this to wipe out a temp buffer that does not contain any
  * marks.
  */
-/*ARGSUSED*/
     void
 wipe_buffer(buf, aucmd)
     buf_T	*buf;
-    int		aucmd;	    /* When TRUE trigger autocommands. */
+    int		aucmd UNUSED;	    /* When TRUE trigger autocommands. */
 {
     if (buf->b_fnum == top_file_num - 1)
 	--top_file_num;
diff --git a/src/charset.c b/src/charset.c
index b6a8926..bac1a20 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1026,13 +1026,12 @@
  * string at start of line.  Warning: *headp is only set if it's a non-zero
  * value, init to 0 before calling.
  */
-/*ARGSUSED*/
     int
 win_lbr_chartabsize(wp, s, col, headp)
     win_T	*wp;
     char_u	*s;
     colnr_T	col;
-    int		*headp;
+    int		*headp UNUSED;
 {
 #ifdef FEAT_LINEBREAK
     int		c;
diff --git a/src/config.h.in b/src/config.h.in
index 900aef8..66baee6 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -30,6 +30,9 @@
 /* Define when __DATE__ " " __TIME__ can be used */
 #undef HAVE_DATE_TIME
 
+/* Define when __attribute__((unused)) can be used */
+#undef HAVE_ATTRIBUTE_UNUSED
+
 /* defined always when using configure */
 #undef UNIX
 
diff --git a/src/configure.in b/src/configure.in
index 8060d4d..aeb69ce 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -2067,6 +2067,11 @@
 	AC_MSG_RESULT(yes); AC_DEFINE(HAVE_DATE_TIME),
 	AC_MSG_RESULT(no))
 
+AC_MSG_CHECKING(whether __attribute__((unused)) is allowed)
+AC_TRY_COMPILE([#include <stdio.h>], [int x __attribute__((unused));],
+	AC_MSG_RESULT(yes); AC_DEFINE(HAVE_ATTRIBUTE_UNUSED),
+	AC_MSG_RESULT(no))
+
 dnl Checks for header files.
 AC_CHECK_HEADER(elf.h, HAS_ELF=1)
 dnl AC_CHECK_HEADER(dwarf.h, SVR4=1)
diff --git a/src/diff.c b/src/diff.c
index b7f0a10..9537a65 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -652,10 +652,9 @@
  * The buffers are written to a file, also for unmodified buffers (the file
  * could have been produced by autocommands, e.g. the netrw plugin).
  */
-/*ARGSUSED*/
     void
 ex_diffupdate(eap)
-    exarg_T	*eap;	    /* can be NULL, it's not used */
+    exarg_T	*eap UNUSED;	    /* can be NULL */
 {
     buf_T	*buf;
     int		idx_orig;
@@ -1094,10 +1093,9 @@
 /*
  * Set options to show difs for the current window.
  */
-/*ARGSUSED*/
     void
 ex_diffthis(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     /* Set 'diff', 'scrollbind' on and 'wrap' off. */
     diff_win_options(curwin, TRUE);
diff --git a/src/edit.c b/src/edit.c
index 2aec226..8411449 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -1447,10 +1447,9 @@
  * Only redraw when there are no characters available.  This speeds up
  * inserting sequences of characters (e.g., for CTRL-R).
  */
-/*ARGSUSED*/
     static void
 ins_redraw(ready)
-    int		ready;	    /* not busy with something */
+    int		ready UNUSED;	    /* not busy with something */
 {
     if (!char_avail())
     {
@@ -1962,10 +1961,9 @@
  * Only matters when there are composing characters.
  * Return TRUE when something was deleted.
  */
-/*ARGSUSED*/
    static int
 del_char_after_col(limit_col)
-    int limit_col;
+    int limit_col UNUSED;
 {
 #ifdef FEAT_MBYTE
     if (enc_utf8 && limit_col >= 0)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index dd66254..11c3ff6 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -43,10 +43,9 @@
 /*
  * ":ascii" and "ga".
  */
-/*ARGSUSED*/
     void
 do_ascii(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     int		c;
     int		cval;
@@ -2373,10 +2372,9 @@
  *   ^?		^H
  * not ^?	^?
  */
-/*ARGSUSED*/
     void
 do_fixdel(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     char_u  *p;
 
@@ -6127,10 +6125,9 @@
 /*
  * ":exusage"
  */
-/*ARGSUSED*/
     void
 ex_exusage(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     do_cmdline_cmd((char_u *)"help ex-cmd-index");
 }
@@ -6138,10 +6135,9 @@
 /*
  * ":viusage"
  */
-/*ARGSUSED*/
     void
 ex_viusage(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     do_cmdline_cmd((char_u *)"help normal-index");
 }
@@ -7154,10 +7150,9 @@
  * Function given to ExpandGeneric() to obtain the sign command
  * expansion.
  */
-/*ARGSUSED*/
     char_u *
 get_sign_name(xp, idx)
-    expand_T	*xp;
+    expand_T	*xp UNUSED;
     int		idx;
 {
     sign_T	*sp;
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index 3599f22..bfa322d 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -680,10 +680,9 @@
 /*
  * ":breaklist".
  */
-/*ARGSUSED*/
     void
 ex_breaklist(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     struct debuggy *bp;
     int		i;
@@ -1342,14 +1341,13 @@
 /*
  * return TRUE if buffer was changed and cannot be abandoned.
  */
-/*ARGSUSED*/
     int
 check_changed(buf, checkaw, mult_win, forceit, allbuf)
     buf_T	*buf;
     int		checkaw;	/* do autowrite if buffer was changed */
     int		mult_win;	/* check also when several wins for the buf */
     int		forceit;
-    int		allbuf;		/* may write all buffers */
+    int		allbuf UNUSED;	/* may write all buffers */
 {
     if (       !forceit
 	    && bufIsChanged(buf)
@@ -1759,12 +1757,11 @@
  *
  * Return FAIL for failure, OK otherwise.
  */
-/*ARGSUSED*/
     static int
 do_arglist(str, what, after)
     char_u	*str;
-    int		what;
-    int		after;		/* 0 means before first one */
+    int		what UNUSED;
+    int		after UNUSED;		/* 0 means before first one */
 {
     garray_T	new_ga;
     int		exp_count;
@@ -2549,11 +2546,10 @@
 
 static void source_callback __ARGS((char_u *fname, void *cookie));
 
-/*ARGSUSED*/
     static void
 source_callback(fname, cookie)
     char_u	*fname;
-    void	*cookie;
+    void	*cookie UNUSED;
 {
     (void)do_source(fname, FALSE, DOSO_NONE);
 }
@@ -2680,10 +2676,9 @@
 /*
  * ":options"
  */
-/*ARGSUSED*/
     void
 ex_options(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     cmd_source((char_u *)SYS_OPTWIN_FILE, NULL);
 }
@@ -3190,10 +3185,9 @@
 /*
  * ":scriptnames"
  */
-/*ARGSUSED*/
     void
 ex_scriptnames(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     int i;
 
@@ -3317,12 +3311,11 @@
  * Return a pointer to the line in allocated memory.
  * Return NULL for end-of-file or some error.
  */
-/* ARGSUSED */
     char_u *
 getsourceline(c, cookie, indent)
-    int		c;		/* not used */
+    int		c UNUSED;
     void	*cookie;
-    int		indent;		/* not used */
+    int		indent UNUSED;
 {
     struct source_cookie *sp = (struct source_cookie *)cookie;
     char_u		*line;
@@ -3649,10 +3642,9 @@
  * ":scriptencoding": Set encoding conversion for a sourced script.
  * Without the multi-byte feature it's simply ignored.
  */
-/*ARGSUSED*/
     void
 ex_scriptencoding(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
 #ifdef FEAT_MBYTE
     struct source_cookie	*sp;
@@ -4101,10 +4093,9 @@
  * Function given to ExpandGeneric() to obtain the possible arguments of the
  * ":language" command.
  */
-/*ARGSUSED*/
     char_u *
 get_lang_arg(xp, idx)
-    expand_T	*xp;
+    expand_T	*xp UNUSED;
     int		idx;
 {
     if (idx == 0)
diff --git a/src/version.c b/src/version.c
index 0dfd5aa..a6e8e2b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -677,6 +677,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    173,
+/**/
     172,
 /**/
     171,
@@ -1623,10 +1625,9 @@
 /*
  * ":intro": clear screen, display intro screen and wait for return.
  */
-/*ARGSUSED*/
     void
 ex_intro(eap)
-    exarg_T	*eap;
+    exarg_T	*eap UNUSED;
 {
     screenclear();
     intro_message(TRUE);
diff --git a/src/vim.h b/src/vim.h
index a9a940b..979f435 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -262,6 +262,14 @@
 # define __PARMS(x) __ARGS(x)
 #endif
 
+/* Mark unused function arguments with UNUSED, so that gcc -Wunused-parameter
+ * can be used to check for mistakes. */
+#ifdef HAVE_ATTRIBUTE_UNUSED
+# define UNUSED __attribute__((unused))
+#else
+# define UNUSED
+#endif
+
 /* if we're compiling in C++ (currently only KVim), the system
  * headers must have the correct prototypes or nothing will build.
  * conversely, our prototypes might clash due to throw() specifiers and