diff --git a/libtelnet/auth-proto.h b/libtelnet/auth-proto.h
index 0bcc0b6..6d3ba7f 100644
--- a/libtelnet/auth-proto.h
+++ b/libtelnet/auth-proto.h
@@ -54,14 +54,6 @@
  * or implied warranty.
  */
 
-#if	!defined(P)
-#ifdef	__STDC__
-#define	P(x)	x
-#else
-#define	P(x)	()
-#endif
-#endif
-
 #ifdef	AUTHENTICATION
 
 Authenticator *findauthenticator(int, int);
diff --git a/libtelnet/enc-proto.h b/libtelnet/enc-proto.h
index a132962..46663c7 100644
--- a/libtelnet/enc-proto.h
+++ b/libtelnet/enc-proto.h
@@ -53,13 +53,6 @@
  * this software for any purpose.  It is provided "as is" without express
  * or implied warranty.
  */
-#if	!defined(P)
-#ifdef	__STDC__
-#define	P(x)	x
-#else
-#define	P(x)	()
-#endif
-#endif
 
 #ifdef	ENCRYPTION
 void encrypt_init(const char *, int);
diff --git a/libtelnet/enc_des.c b/libtelnet/enc_des.c
index 93392a7..5ac693b 100644
--- a/libtelnet/enc_des.c
+++ b/libtelnet/enc_des.c
@@ -116,14 +116,14 @@ struct keyidlist {
 #define	FB64_IV_BAD	3
 
 
-void fb64_stream_iv P((Block, struct stinfo *));
-void fb64_init P((struct fb *));
-static int fb64_start P((struct fb *, int, int));
-int fb64_is P((unsigned char *, int, struct fb *));
-int fb64_reply P((unsigned char *, int, struct fb *));
-static void fb64_session P((Session_Key *, int, struct fb *));
-void fb64_stream_key P((Block, struct stinfo *));
-int fb64_keyid P((int, unsigned char *, int *, struct fb *));
+void fb64_stream_iv(Block, struct stinfo *);
+void fb64_init(struct fb *);
+static int fb64_start(struct fb *, int, int);
+int fb64_is(unsigned char *, int, struct fb *);
+int fb64_reply(unsigned char *, int, struct fb *);
+static void fb64_session(Session_Key *, int, struct fb *);
+void fb64_stream_key(Block, struct stinfo *);
+int fb64_keyid(int, unsigned char *, int *, struct fb *);
 
 void
 cfb64_init(int server __unused)
diff --git a/libtelnet/encrypt.c b/libtelnet/encrypt.c
index d57fd7f..9dffefd 100644
--- a/libtelnet/encrypt.c
+++ b/libtelnet/encrypt.c
@@ -76,8 +76,8 @@ static const char sccsid[] = "@(#)encrypt.c	8.2 (Berkeley) 5/30/95";
  * These functions pointers point to the current routines
  * for encrypting and decrypting data.
  */
-void	(*encrypt_output) P((unsigned char *, int));
-int	(*decrypt_input) P((int));
+void	(*encrypt_output)(unsigned char *, int);
+int	(*decrypt_input)(int);
 
 int EncryptType(char *type, char *mode);
 int EncryptStart(char *mode);
diff --git a/libtelnet/kerberos.c b/libtelnet/kerberos.c
index a6805b8..39b2dd5 100644
--- a/libtelnet/kerberos.c
+++ b/libtelnet/kerberos.c
@@ -72,8 +72,8 @@ static const char sccsid[] = "@(#)kerberos.c	8.3 (Berkeley) 5/30/95";
 #include "auth.h"
 #include "misc.h"
 
-int kerberos4_cksum P((unsigned char *, int));
-int kuserok P((AUTH_DAT *, char *));
+int kerberos4_cksum(unsigned char *, int);
+int kuserok(AUTH_DAT *, char *);
 
 extern int auth_debug_mode;
 
diff --git a/libtelnet/krb4encpwd.c b/libtelnet/krb4encpwd.c
index 8b21def..e0530f6 100644
--- a/libtelnet/krb4encpwd.c
+++ b/libtelnet/krb4encpwd.c
@@ -87,8 +87,8 @@ static char sccsid[] = "@(#)krb4encpwd.c	8.3 (Berkeley) 5/30/95";
 #include "auth.h"
 #include "misc.h"
 
-int krb_mk_encpwd_req P((KTEXT, char *, char *, char *, char *, char *, char *));
-int krb_rd_encpwd_req P((KTEXT, char *, char *, u_long, AUTH_DAT *, char *, char *, char *, char *));
+int krb_mk_encpwd_req(KTEXT, char *, char *, char *, char *, char *, char *);
+int krb_rd_encpwd_req(KTEXT, char *, char *, u_long, AUTH_DAT *, char *, char *, char *, char *);
 
 extern auth_debug_mode;
 
diff --git a/libtelnet/misc-proto.h b/libtelnet/misc-proto.h
index 5f4f9fc..aea753c 100644
--- a/libtelnet/misc-proto.h
+++ b/libtelnet/misc-proto.h
@@ -57,14 +57,6 @@
 #ifndef	__MISC_PROTO__
 #define	__MISC_PROTO__
 
-#if	!defined(P)
-#ifdef	__STDC__
-#define	P(x)	x
-#else
-#define	P(x)	()
-#endif
-#endif
-
 void auth_encrypt_init(char *, char *, const char *, int);
 void auth_encrypt_connect(int);
 void printd(const unsigned char *, int);
diff --git a/telnet/commands.c b/telnet/commands.c
index 8b30e36..dd14487 100644
--- a/telnet/commands.c
+++ b/telnet/commands.c
@@ -86,13 +86,13 @@ static const char sccsid[] = "@(#)commands.c	8.4 (Berkeley) 5/30/95";
 typedef int (*intrtn_t)(int, char **);
 
 #ifdef	AUTHENTICATION
-extern int auth_togdebug P((int));
+extern int auth_togdebug(int);
 #endif
 #ifdef	ENCRYPTION
-extern int EncryptAutoEnc P((int));
-extern int EncryptAutoDec P((int));
-extern int EncryptDebug P((int));
-extern int EncryptVerbose P((int));
+extern int EncryptAutoEnc(int);
+extern int EncryptAutoDec(int);
+extern int EncryptDebug(int);
+extern int EncryptVerbose(int);
 #endif	/* ENCRYPTION */
 #if	defined(IPPROTO_IP) && defined(IP_TOS)
 int tos = -1;
@@ -289,12 +289,12 @@ struct sendlist {
 
 
 static int
-	send_esc P((void)),
-	send_help P((void)),
-	send_docmd P((char *)),
-	send_dontcmd P((char *)),
-	send_willcmd P((char *)),
-	send_wontcmd P((char *));
+	send_esc(void),
+	send_help(void),
+	send_docmd(char *),
+	send_dontcmd(char *),
+	send_willcmd(char *),
+	send_wontcmd(char *);
 
 static struct sendlist Sendlist[] = {
     { "ao",	"Send Telnet Abort output",	1, 0, NULL, 2, AO },
@@ -1514,18 +1514,18 @@ struct envlist {
 };
 
 extern struct env_lst *
-	env_define P((const unsigned char *, unsigned char *));
+	env_define(const unsigned char *, unsigned char *);
 extern void
-	env_undefine P((unsigned char *)),
-	env_export P((const unsigned char *)),
-	env_unexport P((const unsigned char *)),
-	env_send P((unsigned char *)),
+	env_undefine(unsigned char *),
+	env_export(const unsigned char *),
+	env_unexport(const unsigned char *),
+	env_send(unsigned char *),
 #if defined(OLD_ENVIRON) && defined(ENV_HACK)
-	env_varval P((unsigned char *)),
+	env_varval(unsigned char *),
 #endif
-	env_list P((void));
+	env_list(void);
 static void
-	env_help P((void));
+	env_help(void);
 
 struct envlist EnvList[] = {
     { "define",	"Define an environment variable",
@@ -1847,11 +1847,11 @@ struct authlist {
 };
 
 extern int
-	auth_enable P((char *)),
-	auth_disable P((char *)),
-	auth_status P((void));
+	auth_enable(char *),
+	auth_disable(char *),
+	auth_status(void);
 static int
-	auth_help P((void));
+	auth_help(void);
 
 struct authlist AuthList[] = {
     { "status",	"Display current status of authentication information",
@@ -1930,18 +1930,18 @@ struct encryptlist {
 };
 
 extern int
-	EncryptEnable P((char *, char *)),
-	EncryptDisable P((char *, char *)),
-	EncryptType P((char *, char *)),
-	EncryptStart P((char *)),
-	EncryptStartInput P((void)),
-	EncryptStartOutput P((void)),
-	EncryptStop P((char *)),
-	EncryptStopInput P((void)),
-	EncryptStopOutput P((void)),
-	EncryptStatus P((void));
+	EncryptEnable(char *, char *),
+	EncryptDisable(char *, char *),
+	EncryptType(char *, char *),
+	EncryptStart(char *),
+	EncryptStartInput(void),
+	EncryptStartOutput(void),
+	EncryptStop(char *),
+	EncryptStopInput(void),
+	EncryptStopOutput(void),
+	EncryptStatus(void);
 static int
-	EncryptHelp P((void));
+	EncryptHelp(void);
 
 struct encryptlist EncryptList[] = {
     { "enable", "Enable encryption. ('encrypt enable ?' for more)",
diff --git a/telnet/externs.h b/telnet/externs.h
index c8ea02c..5ecf114 100644
--- a/telnet/externs.h
+++ b/telnet/externs.h
@@ -148,8 +148,8 @@ extern char
     options[],		/* All the little options */
     *hostname;		/* Who are we connected to? */
 #ifdef	ENCRYPTION
-extern void (*encrypt_output) P((unsigned char *, int));
-extern int (*decrypt_input) P((int));
+extern void (*encrypt_output)(unsigned char *, int);
+extern int (*decrypt_input)(int);
 #endif	/* ENCRYPTION */
 
 /*
@@ -222,7 +222,7 @@ extern int (*decrypt_input) P((int));
 
 #ifdef	SIGINFO
 extern SIG_FUNC_RET
-    ayt_status P((void));
+    ayt_status(void);
 #endif
 
 extern FILE
@@ -230,113 +230,113 @@ extern FILE
 extern unsigned char
     NetTraceFile[];	/* Name of file where debugging output goes */
 extern void
-    SetNetTrace P((char *));	/* Function to change where debugging goes */
+    SetNetTrace(char *);	/* Function to change where debugging goes */
 
 extern jmp_buf
     peerdied,
     toplevel;		/* For error conditions. */
 
 extern void
-    command P((int, const char *, int)),
-    Dump P((char, unsigned char *, int)),
-    env_init P((void)),
-    Exit P((int)),
-    ExitString P((const char *, int)),
-    init_network P((void)),
-    init_sys P((void)),
-    init_telnet P((void)),
-    init_terminal P((void)),
-    intp P((void)),
-    optionstatus P((void)),
-    printoption P((const char *, int, int)),
-    printsub P((char, unsigned char *, int)),
-    quit P((void)),
-    sendabort P((void)),
-    sendbrk P((void)),
-    sendeof P((void)),
-    sendsusp P((void)),
-    sendnaws P((void)),
-    sendayt P((void)),
-    setconnmode P((int)),
-    setcommandmode P((void)),
-    set_escape_char P((char *s)),
-    setneturg P((void)),
-    sys_telnet_init P((void)),
-    telnet P((char *)),
-    tel_enter_binary P((int)),
-    tel_leave_binary P((int)),
-    TerminalFlushOutput P((void)),
-    TerminalNewMode P((int)),
-    TerminalRestoreState P((void)),
-    TerminalSaveState P((void)),
-    TerminalDefaultChars P((void)),
-    TerminalSpeeds P((long *, long *)),
-    tninit P((void)),
-    upcase P((char *)),
-    willoption P((int)),
-    wontoption P((int));
+    command(int, const char *, int),
+    Dump(char, unsigned char *, int),
+    env_init(void),
+    Exit(int),
+    ExitString(const char *, int),
+    init_network(void),
+    init_sys(void),
+    init_telnet(void),
+    init_terminal(void),
+    intp(void),
+    optionstatus(void),
+    printoption(const char *, int, int),
+    printsub(char, unsigned char *, int),
+    quit(void),
+    sendabort(void),
+    sendbrk(void),
+    sendeof(void),
+    sendsusp(void),
+    sendnaws(void),
+    sendayt(void),
+    setconnmode(int),
+    setcommandmode(void),
+    set_escape_char(char *s),
+    setneturg(void),
+    sys_telnet_init(void),
+    telnet(char *),
+    tel_enter_binary(int),
+    tel_leave_binary(int),
+    TerminalFlushOutput(void),
+    TerminalNewMode(int),
+    TerminalRestoreState(void),
+    TerminalSaveState(void),
+    TerminalDefaultChars(void),
+    TerminalSpeeds(long *, long *),
+    tninit(void),
+    upcase(char *),
+    willoption(int),
+    wontoption(int);
 
 extern void
-    send_do P((int, int)),
-    send_dont P((int, int)),
-    send_will P((int, int)),
-    send_wont P((int, int));
+    send_do(int, int),
+    send_dont(int, int),
+    send_will(int, int),
+    send_wont(int, int);
 
 extern void
-    lm_will P((unsigned char *, int)),
-    lm_wont P((unsigned char *, int)),
-    lm_do P((unsigned char *, int)),
-    lm_dont P((unsigned char *, int)),
-    lm_mode P((unsigned char *, int, int));
+    lm_will(unsigned char *, int),
+    lm_wont(unsigned char *, int),
+    lm_do(unsigned char *, int),
+    lm_dont(unsigned char *, int),
+    lm_mode(unsigned char *, int, int);
 
 extern void
-    slc_init P((void)),
-    slcstate P((void)),
-    slc_mode_export P((void)),
-    slc_mode_import P((int)),
-    slc_import P((int)),
-    slc_export P((void)),
-    slc P((unsigned char *, int)),
-    slc_check P((void)),
-    slc_start_reply P((void)),
-    slc_add_reply P((unsigned char, unsigned char, cc_t)),
-    slc_end_reply P((void));
+    slc_init(void),
+    slcstate(void),
+    slc_mode_export(void),
+    slc_mode_import(int),
+    slc_import(int),
+    slc_export(void),
+    slc(unsigned char *, int),
+    slc_check(void),
+    slc_start_reply(void),
+    slc_add_reply(unsigned char, unsigned char, cc_t),
+    slc_end_reply(void);
 extern int
-    getconnmode P((void)),
-    opt_welldefined P((const char *)),
-    NetClose P((int)),
-    netflush P((void)),
-    process_rings P((int, int, int, int, int, int)),
-    rlogin_susp P((void)),
-    SetSockOpt P((int, int, int, int)),
-    slc_update P((void)),
-    stilloob P((void)),
-    telrcv P((void)),
-    TerminalRead P((char *, int)),
-    TerminalWrite P((char *, int)),
-    TerminalAutoFlush P((void)),
-    TerminalWindowSize P((long *, long *)),
-    TerminalSpecialChars P((int)),
-    tn P((int, char **)),
-    ttyflush P((int));
+    getconnmode(void),
+    opt_welldefined(const char *),
+    NetClose(int),
+    netflush(void),
+    process_rings(int, int, int, int, int, int),
+    rlogin_susp(void),
+    SetSockOpt(int, int, int, int),
+    slc_update(void),
+    stilloob(void),
+    telrcv(void),
+    TerminalRead(char *, int),
+    TerminalWrite(char *, int),
+    TerminalAutoFlush(void),
+    TerminalWindowSize(long *, long *),
+    TerminalSpecialChars(int),
+    tn(int, char **),
+    ttyflush(int);
 
 extern void
-    env_opt P((unsigned char *, int)),
-    env_opt_start P((void)),
-    env_opt_start_info P((void)),
-    env_opt_add P((unsigned char *)),
-    env_opt_end P((int));
+    env_opt(unsigned char *, int),
+    env_opt_start(void),
+    env_opt_start_info(void),
+    env_opt_add(unsigned char *),
+    env_opt_end(int);
 
 extern unsigned char
-    *env_default P((int, int)),
-    *env_getvalue P((const unsigned char *));
+    *env_default(int, int),
+    *env_getvalue(const unsigned char *);
 
 extern int
-    get_status P((char *)),
-    dosynch P((char *));
+    get_status(char *),
+    dosynch(char *);
 
 extern cc_t
-    *tcval P((int));
+    *tcval(int);
 
 #ifndef	USE_TERMIO
 
@@ -486,6 +486,6 @@ extern Ring
     ttyiring;
 
 extern void
-    xmitAO P((void)),
-    xmitEC P((void)),
-    xmitEL P((void));
+    xmitAO(void),
+    xmitEC(void),
+    xmitEL(void);
diff --git a/telnet/ring.h b/telnet/ring.h
index 48606e5..516b7a5 100644
--- a/telnet/ring.h
+++ b/telnet/ring.h
@@ -73,35 +73,35 @@ typedef struct {
 
 /* Initialization routine */
 extern int
-	ring_init P((Ring *ring, unsigned char *buffer, int count));
+	ring_init(Ring *ring, unsigned char *buffer, int count);
 
 /* Data movement routines */
 extern void
-	ring_supply_data P((Ring *ring, unsigned char *buffer, int count));
+	ring_supply_data(Ring *ring, unsigned char *buffer, int count);
 #ifdef notdef
 extern void
-	ring_consume_data P((Ring *ring, unsigned char *buffer, int count));
+	ring_consume_data(Ring *ring, unsigned char *buffer, int count);
 #endif
 
 /* Buffer state transition routines */
 extern void
-	ring_supplied P((Ring *ring, int count)),
-	ring_consumed P((Ring *ring, int count));
+	ring_supplied(Ring *ring, int count),
+	ring_consumed(Ring *ring, int count);
 
 /* Buffer state query routines */
 extern int
-	ring_at_mark P((Ring *)),
-	ring_empty_count P((Ring *ring)),
-	ring_empty_consecutive P((Ring *ring)),
-	ring_full_count P((Ring *ring)),
-	ring_full_consecutive P((Ring *ring));
+	ring_at_mark(Ring *),
+	ring_empty_count(Ring *ring),
+	ring_empty_consecutive(Ring *ring),
+	ring_full_count(Ring *ring),
+	ring_full_consecutive(Ring *ring);
 
 #ifdef	ENCRYPTION
 extern void
-	ring_encrypt P((Ring *ring, void (*func)(unsigned char *, int))),
-	ring_clearto P((Ring *ring));
+	ring_encrypt(Ring *ring, void (*func)(unsigned char *, int)),
+	ring_clearto(Ring *ring);
 #endif	/* ENCRYPTION */
 
 extern void
-	ring_clear_mark P((Ring *)),
-	ring_mark P((Ring *));
+	ring_clear_mark(Ring *),
+	ring_mark(Ring *);
diff --git a/telnetd/ext.h b/telnetd/ext.h
index d9becde..448ba68 100644
--- a/telnetd/ext.h
+++ b/telnetd/ext.h
@@ -80,115 +80,107 @@ extern int	pty, net;
 extern char	line[16];
 extern int	SYNCHing;		/* we are in TELNET SYNCH mode */
 
-#ifndef	P
-# ifdef	__STDC__
-#  define P(x)	x
-# else
-#  define P(x)	()
-# endif
-#endif
-
 extern void
-	_termstat P((void)),
-	add_slc P((char, char, cc_t)),
-	check_slc P((void)),
-	change_slc P((char, char, cc_t)),
-	cleanup P((int)),
-	clientstat P((int, int, int)),
-	copy_termbuf P((char *, size_t)),
-	deferslc P((void)),
-	defer_terminit P((void)),
-	do_opt_slc P((unsigned char *, int)),
-	doeof P((void)),
-	dooption P((int)),
-	dontoption P((int)),
-	edithost P((char *, char *)),
-	fatal P((int, const char *)),
-	fatalperror P((int, const char *)),
-	get_slc_defaults P((void)),
-	init_env P((void)),
-	init_termbuf P((void)),
-	interrupt P((void)),
-	localstat P((void)),
-	flowstat P((void)),
-	netclear P((void)),
-	netflush P((void)),
+	_termstat(void),
+	add_slc(char, char, cc_t),
+	check_slc(void),
+	change_slc(char, char, cc_t),
+	cleanup(int),
+	clientstat(int, int, int),
+	copy_termbuf(char *, size_t),
+	deferslc(void),
+	defer_terminit(void),
+	do_opt_slc(unsigned char *, int),
+	doeof(void),
+	dooption(int),
+	dontoption(int),
+	edithost(char *, char *),
+	fatal(int, const char *),
+	fatalperror(int, const char *),
+	get_slc_defaults(void),
+	init_env(void),
+	init_termbuf(void),
+	interrupt(void),
+	localstat(void),
+	flowstat(void),
+	netclear(void),
+	netflush(void),
 #ifdef DIAGNOSTICS
-	printoption P((const char *, int)),
-	printdata P((const char *, char *, int)),
-	printsub P((char, unsigned char *, int)),
+	printoption(const char *, int),
+	printdata(const char *, char *, int),
+	printsub(char, unsigned char *, int),
 #endif
-	process_slc P((unsigned char, unsigned char, cc_t)),
-	ptyflush P((void)),
-	putchr P((int)),
-	putf P((char *, char *)),
-	recv_ayt P((void)),
-	send_do P((int, int)),
-	send_dont P((int, int)),
-	send_slc P((void)),
-	send_status P((void)),
-	send_will P((int, int)),
-	send_wont P((int, int)),
-	sendbrk P((void)),
-	sendsusp P((void)),
-	set_termbuf P((void)),
-	start_login P((char *, int, char *)),
-	start_slc P((int)),
+	process_slc(unsigned char, unsigned char, cc_t),
+	ptyflush(void),
+	putchr(int),
+	putf(char *, char *),
+	recv_ayt(void),
+	send_do(int, int),
+	send_dont(int, int),
+	send_slc(void),
+	send_status(void),
+	send_will(int, int),
+	send_wont(int, int),
+	sendbrk(void),
+	sendsusp(void),
+	set_termbuf(void),
+	start_login(char *, int, char *),
+	start_slc(int),
 #ifdef	AUTHENTICATION
-	start_slave P((char *)),
+	start_slave(char *),
 #else
-	start_slave P((char *, int, char *)),
+	start_slave(char *, int, char *),
 #endif
-	suboption P((void)),
-	telrcv P((void)),
-	ttloop P((void)),
-	tty_binaryin P((int)),
-	tty_binaryout P((int));
+	suboption(void),
+	telrcv(void),
+	ttloop(void),
+	tty_binaryin(int),
+	tty_binaryout(int);
 
 extern int
-	end_slc P((unsigned char **)),
-	getnpty P((void)),
+	end_slc(unsigned char **),
+	getnpty(void),
 #ifndef convex
-	getpty P((int *)),
+	getpty(int *),
 #endif
-	login_tty P((int)),
-	spcset P((int, cc_t *, cc_t **)),
-	stilloob P((int)),
-	terminit P((void)),
-	termstat P((void)),
-	tty_flowmode P((void)),
-	tty_restartany P((void)),
-	tty_isbinaryin P((void)),
-	tty_isbinaryout P((void)),
-	tty_iscrnl P((void)),
-	tty_isecho P((void)),
-	tty_isediting P((void)),
-	tty_islitecho P((void)),
-	tty_isnewmap P((void)),
-	tty_israw P((void)),
-	tty_issofttab P((void)),
-	tty_istrapsig P((void)),
-	tty_linemode P((void));
+	login_tty(int),
+	spcset(int, cc_t *, cc_t **),
+	stilloob(int),
+	terminit(void),
+	termstat(void),
+	tty_flowmode(void),
+	tty_restartany(void),
+	tty_isbinaryin(void),
+	tty_isbinaryout(void),
+	tty_iscrnl(void),
+	tty_isecho(void),
+	tty_isediting(void),
+	tty_islitecho(void),
+	tty_isnewmap(void),
+	tty_israw(void),
+	tty_issofttab(void),
+	tty_istrapsig(void),
+	tty_linemode(void);
 
 extern void
-	tty_rspeed P((int)),
-	tty_setecho P((int)),
-	tty_setedit P((int)),
-	tty_setlinemode P((int)),
-	tty_setlitecho P((int)),
-	tty_setsig P((int)),
-	tty_setsofttab P((int)),
-	tty_tspeed P((int)),
-	willoption P((int)),
-	wontoption P((int));
+	tty_rspeed(int),
+	tty_setecho(int),
+	tty_setedit(int),
+	tty_setlinemode(int),
+	tty_setlitecho(int),
+	tty_setsig(int),
+	tty_setsofttab(int),
+	tty_tspeed(int),
+	willoption(int),
+	wontoption(int);
 
-int	output_data __P((const char *, ...)) __printflike(1, 2);
-void	output_datalen __P((const char *, int));
-void	startslave __P((char *, int, char *));
+int	output_data(const char *, ...) __printflike(1, 2);
+void	output_datalen(const char *, int);
+void	startslave(char *, int, char *);
 
 #ifdef	ENCRYPTION
-extern void	(*encrypt_output) P((unsigned char *, int));
-extern int	(*decrypt_input) P((int));
+extern void	(*encrypt_output)(unsigned char *, int);
+extern int	(*decrypt_input)(int);
 extern char	*nclearto;
 #endif	/* ENCRYPTION */
 
diff --git a/telnetd/sys_term.c b/telnetd/sys_term.c
index 9edde84..eff9b1e 100644
--- a/telnetd/sys_term.c
+++ b/telnetd/sys_term.c
@@ -140,9 +140,9 @@ struct termios termbuf, termbuf2;	/* pty control structure */
 #include <sys/types.h>
 #include <libutil.h>
 
-int cleanopen __P((char *));
-void scrub_env __P((void));
-static char **addarg __P((char **, const char *));
+int cleanopen(char *);
+void scrub_env(void);
+static char **addarg(char **, const char *);
 
 /*
  * init_termbuf()
diff --git a/telnetd/telnetd.c b/telnetd/telnetd.c
index 7527b7e..02f21cf 100644
--- a/telnetd/telnetd.c
+++ b/telnetd/telnetd.c
@@ -82,11 +82,11 @@ int debug = 0;
 int keepalive = 1;
 const char *altlogin;
 
-void doit __P((struct sockaddr *));
-int terminaltypeok __P((char *));
-void startslave __P((char *, int, char *));
-extern void usage P((void));
-static void _gettermname __P((void));
+void doit(struct sockaddr *);
+int terminaltypeok(char *);
+void startslave(char *, int, char *);
+extern void usage(void);
+static void _gettermname(void);
 
 /*
  * The string to pass to getopt().  We do it this way so
@@ -123,7 +123,7 @@ int family = AF_INET;
 char *hostname;
 char host_name[MAXHOSTNAMELEN];
 
-extern void telnet P((int, int, char *));
+extern void telnet(int, int, char *);
 
 int level;
 char user_name[256];