diff --git a/usr.bin/mail/cmd1.c b/usr.bin/mail/cmd1.c
index cace03df9aab..0689c1eb0cb5 100644
--- a/usr.bin/mail/cmd1.c
+++ b/usr.bin/mail/cmd1.c
@@ -211,7 +211,7 @@ printhead(int mesg)
  * Print out the value of dot.
  */
 int
-pdot(void)
+pdot(void *arg __unused)
 {
 	printf("%td\n", dot - &message[0] + 1);
 	return (0);
@@ -221,7 +221,7 @@ pdot(void)
  * Print out all the possible commands.
  */
 int
-pcmdlist(void)
+pcmdlist(void *arg __unused)
 {
 	extern const struct cmd cmdtab[];
 	const struct cmd *cp;
@@ -439,7 +439,7 @@ mboxit(void *v)
  * List the folders the user currently has.
  */
 int
-folders(void)
+folders(void *arg __unused)
 {
 	char dirname[PATHSIZE];
 	char *cmd;
diff --git a/usr.bin/mail/cmd2.c b/usr.bin/mail/cmd2.c
index 08b7a252b974..2c0f8d55e299 100644
--- a/usr.bin/mail/cmd2.c
+++ b/usr.bin/mail/cmd2.c
@@ -360,7 +360,7 @@ undeletecmd(void *v)
  * Interactively dump core on "core"
  */
 int
-core(void)
+core(void *arg __unused)
 {
 	int pid;
 
@@ -386,8 +386,9 @@ core(void)
  * Clobber as many bytes of stack as the user requests.
  */
 int
-clobber(char **argv)
+clobber(void *arg)
 {
+	char **argv = arg;
 	int times;
 
 	if (argv[0] == 0)
diff --git a/usr.bin/mail/cmd3.c b/usr.bin/mail/cmd3.c
index 68afbaa56913..2b4a20b96bb5 100644
--- a/usr.bin/mail/cmd3.c
+++ b/usr.bin/mail/cmd3.c
@@ -51,7 +51,7 @@ __FBSDID("$FreeBSD$");
  * and forking a sh -c
  */
 int
-shell(char *str)
+shell(void *str)
 {
 	sig_t sigint = signal(SIGINT, SIG_IGN);
 	char *sh;
@@ -74,7 +74,7 @@ shell(char *str)
  */
 /*ARGSUSED*/
 int
-dosh(char *str __unused)
+dosh(void *str __unused)
 {
 	sig_t sigint = signal(SIGINT, SIG_IGN);
 	char *sh;
@@ -146,7 +146,7 @@ overf:
  */
 
 int
-help(void)
+help(void *arg __unused)
 {
 	int c;
 	FILE *f;
@@ -530,7 +530,7 @@ diction(const void *a, const void *b)
 
 /*ARGSUSED*/
 int
-null(int e __unused)
+null(void *arg __unused)
 {
 	return (0);
 }
@@ -540,8 +540,9 @@ null(int e __unused)
  * the current file.
  */
 int
-file(char **argv)
+file(void *arg)
 {
+	char **argv = arg;
 
 	if (argv[0] == NULL) {
 		newfileinfo(0);
@@ -557,8 +558,9 @@ file(char **argv)
  * Expand file names like echo
  */
 int
-echo(char **argv)
+echo(void *arg)
 {
+	char **argv = arg;
 	char **ap, *cp;
 
 	for (ap = argv; *ap != NULL; ap++) {
@@ -574,7 +576,7 @@ echo(char **argv)
 }
 
 int
-Respond(int *msgvec)
+Respond(void *msgvec)
 {
 	if (value("Replyall") == NULL && value("flipr") == NULL)
 		return (doRespond(msgvec));
@@ -625,8 +627,9 @@ doRespond(int msgvec[])
  * .mailrc and do some things if sending, others if receiving.
  */
 int
-ifcmd(char **argv)
+ifcmd(void *arg)
 {
+	char **argv = arg;
 	char *cp;
 
 	if (cond != CANY) {
@@ -656,7 +659,7 @@ ifcmd(char **argv)
  * flip over the conditional flag.
  */
 int
-elsecmd(void)
+elsecmd(void *arg __unused)
 {
 
 	switch (cond) {
@@ -684,7 +687,7 @@ elsecmd(void)
  * End of if statement.  Just set cond back to anything.
  */
 int
-endifcmd(void)
+endifcmd(void *arg __unused)
 {
 
 	if (cond == CANY) {
@@ -699,8 +702,9 @@ endifcmd(void)
  * Set the list of alternate names.
  */
 int
-alternates(char **namelist)
+alternates(void *arg)
 {
+	char **namelist = arg;
 	int c;
 	char **ap, **ap2, *cp;
 
diff --git a/usr.bin/mail/collect.c b/usr.bin/mail/collect.c
index d56f460a8690..e8249a10f867 100644
--- a/usr.bin/mail/collect.c
+++ b/usr.bin/mail/collect.c
@@ -199,7 +199,7 @@ cont:
 			/*
 			 * Dump core.
 			 */
-			core();
+			core(NULL);
 			break;
 		case '!':
 			/*
diff --git a/usr.bin/mail/def.h b/usr.bin/mail/def.h
index 02b84478456b..fd41081797c6 100644
--- a/usr.bin/mail/def.h
+++ b/usr.bin/mail/def.h
@@ -106,7 +106,7 @@ struct message {
  */
 struct cmd {
 	const	char *c_name;		/* Name of command */
-	int	(*c_func)();		/* Implementor of the command */
+	int	(*c_func)(void *);	/* Implementor of the command */
 	short	c_argtype;		/* Type of arglist (see below) */
 	short	c_msgflag;		/* Required flags of messages */
 	short	c_msgmask;		/* Relevant flags of messages */
diff --git a/usr.bin/mail/edit.c b/usr.bin/mail/edit.c
index e8d6fcb12ccc..bc7f4beb29fb 100644
--- a/usr.bin/mail/edit.c
+++ b/usr.bin/mail/edit.c
@@ -51,7 +51,7 @@ __FBSDID("$FreeBSD$");
  * Edit a message list.
  */
 int
-editor(int *msgvec)
+editor(void *msgvec)
 {
 
 	return (edit1(msgvec, 'e'));
@@ -61,7 +61,7 @@ editor(int *msgvec)
  * Invoke the visual editor on a message list.
  */
 int
-visual(int *msgvec)
+visual(void *msgvec)
 {
 
 	return (edit1(msgvec, 'v'));
diff --git a/usr.bin/mail/extern.h b/usr.bin/mail/extern.h
index aa31733dd26a..4f06f77f18a2 100644
--- a/usr.bin/mail/extern.h
+++ b/usr.bin/mail/extern.h
@@ -75,12 +75,12 @@ char	*yanklogin(char *, char *);
 int	 Fclose(FILE *);
 int	 More(void *);
 int	 Pclose(FILE *);
-int	 Respond(int *);
+int	 Respond(void *);
 int	 Type(void *);
 int	 doRespond(int *);
 int	 dorespond(int *);
 void	 alter(char *);
-int	 alternates(char **);
+int	 alternates(void *);
 void	 announce(void);
 int	 append(struct message *, FILE *);
 int	 argcount(char **);
@@ -90,7 +90,7 @@ void	 brokpipe(int);
 int	 charcount(char *, int);
 int	 check(int, int);
 void	 clob1(int);
-int	 clobber(char **);
+int	 clobber(void *);
 void	 close_all_files(void);
 int	 cmatch(char *, char *);
 void	 collhup(int);
@@ -98,32 +98,32 @@ void	 collint(int);
 void	 collstop(int);
 void	 commands(void);
 int	 copycmd(void *v);
-int	 core(void);
+int	 core(void *);
 int	 count(struct name *);
 int	 deletecmd(void *);
 int	 delm(int *);
 int	 deltype(void *);
 void	 demail(void);
 int	 diction(const void *, const void *);
-int	 dosh(char *);
-int	 echo(char **);
+int	 dosh(void *);
+int	 echo(void *);
 int	 edit1(int *, int);
-int	 editor(int *);
+int	 editor(void *);
 void	 edstop(void);
-int	 elsecmd(void);
-int	 endifcmd(void);
+int	 elsecmd(void *);
+int	 endifcmd(void *);
 int	 evalcol(int);
 int	 execute(char *, int);
 int	 exwrite(char *, FILE *, int);
 void	 fail(const char *, const char *);
-int	 file(char **);
+int	 file(void *);
 struct grouphead *
 	 findgroup(char *);
 void	 findmail(char *, char *, int);
 int	 first(int, int);
 void	 fixhead(struct header *, struct name *);
 void	 fmt(const char *, struct name *, FILE *, int);
-int	 folders(void);
+int	 folders(void *);
 int	 forward(char *, FILE *, char *, int);
 void	 free_child(int);
 int	 from(void *);
@@ -139,9 +139,9 @@ void	 hangup(int);
 int	 hash(const char *);
 void	 hdrstop(int);
 int	 headers(void *);
-int	 help(void);
+int	 help(void *);
 void	 holdsigs(void);
-int	 ifcmd(char **);
+int	 ifcmd(void *);
 int	 igcomp(const void *, const void *);
 int	 igfield(void *);
 int	 ignore1(char **, struct ignoretab *, const char *);
@@ -178,10 +178,10 @@ int	 metamess(int, int);
 int	 more(void *);
 int	 newfileinfo(int);
 int	 next(void *);
-int	 null(int);
+int	 null(void *);
 void	 parse(char *, struct headline *, char *);
-int	 pcmdlist(void);
-int	 pdot(void);
+int	 pcmdlist(void *);
+int	 pdot(void *);
 void	 prepare_child(sigset_t *, int, int);
 int	 preserve(void *);
 void	 prettyprint(struct name *);
@@ -189,9 +189,9 @@ void	 printgroup(char *);
 void	 printhead(int);
 int	 puthead(struct header *, FILE *, int);
 int	 putline(FILE *, char *, int);
-int	 pversion(int);
+int	 pversion(void *);
 void	 quit(void);
-int	 quitcmd(void);
+int	 quitcmd(void *);
 int	 readline(FILE *, char *, int);
 void	 register_file(FILE *, int, int);
 void	 regret(int);
@@ -213,16 +213,16 @@ int	 schdir(void *);
 int	 screensize(void);
 int	 scroll(void *);
 int	 sendmessage(struct message *, FILE *, struct ignoretab *, char *);
-int	 sendmail(char *);
+int	 sendmail(void *);
 int	 set(void *);
 int	 setfile(char *);
 void	 setmsize(int);
 void	 setptr(FILE *, off_t);
 void	 setscreensize(void);
-int	 shell(char *);
+int	 shell(void *);
 void	 sigchild(int);
 void	 sort(char **);
-int	 source(char **);
+int	 source(void *);
 void	 spreserve(void);
 void	 sreset(void);
 int	 start_command(char *, sigset_t *, int, int, ...);
@@ -245,7 +245,7 @@ void	 unregister_file(FILE *);
 int	 unset(void *);
 int	 unstack(void);
 void	 vfree(char *);
-int	 visual(int *);
+int	 visual(void *);
 int	 wait_child(int);
 int	 wait_command(int);
 int	 writeback(FILE *);
diff --git a/usr.bin/mail/lex.c b/usr.bin/mail/lex.c
index 77004e52f28c..dfca9edeab8e 100644
--- a/usr.bin/mail/lex.c
+++ b/usr.bin/mail/lex.c
@@ -672,7 +672,7 @@ newfileinfo(int omsgCount)
  */
 
 int
-pversion(int e __unused)
+pversion(void *arg __unused)
 {
 
 	printf("Version %s\n", version);
diff --git a/usr.bin/mail/quit.c b/usr.bin/mail/quit.c
index 7b44f386bd53..e9d93285c65e 100644
--- a/usr.bin/mail/quit.c
+++ b/usr.bin/mail/quit.c
@@ -51,7 +51,7 @@ __FBSDID("$FreeBSD$");
  * The "quit" command.
  */
 int
-quitcmd(void)
+quitcmd(void *arg __unused)
 {
 	/*
 	 * If we are sourcing, then return 1 so execute() can handle it.
diff --git a/usr.bin/mail/send.c b/usr.bin/mail/send.c
index 70bc5261f805..702dbd031216 100644
--- a/usr.bin/mail/send.c
+++ b/usr.bin/mail/send.c
@@ -268,7 +268,7 @@ mail(struct name *to, struct name *cc, struct name *bcc, struct name *smopts,
  * the mail routine below.
  */
 int
-sendmail(char *str)
+sendmail(void *str)
 {
 	struct header head;
 
diff --git a/usr.bin/mail/util.c b/usr.bin/mail/util.c
index 558b47245c77..7187d1b520f9 100644
--- a/usr.bin/mail/util.c
+++ b/usr.bin/mail/util.c
@@ -265,8 +265,9 @@ static struct sstack sstack[SSTACK_SIZE];
  * that they are no longer reading from a tty (in all probability).
  */
 int
-source(char **arglist)
+source(void *arg)
 {
+	char **arglist = arg;
 	FILE *fi;
 	char *cp;