diff --git a/usr.bin/doscmd/cpu.c b/usr.bin/doscmd/cpu.c
index ea60ff128d76..f69af868e6fd 100644
--- a/usr.bin/doscmd/cpu.c
+++ b/usr.bin/doscmd/cpu.c
@@ -44,26 +44,26 @@ static void		write_word(u_int32_t, u_int16_t);
 ** Hardware /0 interrupt
 */
 void
-int00(regcontext_t *REGS)
+int00(regcontext_t *REGS __unused)
 {
     debug(D_ALWAYS, "Divide by 0 in DOS program!\n");
     exit(1);
 }
 
 void
-int01(regcontext_t *REGS)
+int01(regcontext_t *REGS __unused)
 {
     debug(D_ALWAYS, "INT 1 with no handler! (single-step/debug)\n");
 }
 
 void
-int03(regcontext_t *REGS)
+int03(regcontext_t *REGS __unused)
 {
     debug(D_ALWAYS, "INT 3 with no handler! (breakpoint)\n");
 }
 
 void
-int0d(regcontext_t *REGS)
+int0d(regcontext_t *REGS __unused)
 {
     debug(D_ALWAYS, "IRQ5 with no handler!\n");
 }
diff --git a/usr.bin/doscmd/cwd.c b/usr.bin/doscmd/cwd.c
index 85269b98fda5..2e5415a3803b 100644
--- a/usr.bin/doscmd/cwd.c
+++ b/usr.bin/doscmd/cwd.c
@@ -80,7 +80,7 @@ static Name_t *names;
  * Initialize the drive to be based at 'base' in the BSD filesystem
  */
 void
-init_path(int drive, u_char *base, u_char *dir)
+init_path(int drive, const u_char *base, const u_char *dir)
 {
     Path_t *d;
 
@@ -233,7 +233,7 @@ dos_makepath(u_char *where, u_char *newpath)
     if (*where != '\\' && *where != '/') {
 	ustrncpy(tmppath, d->cwd, 1024);
 	if (d->cwd[1])
-	    ustrncat(tmppath, (u_char *)"/", 1024 - ustrlen(tmppath));
+	    ustrncat(tmppath, "/", 1024 - ustrlen(tmppath));
 	ustrncat(tmppath, where, 1024 - ustrlen(tmppath));
     } else {
 	ustrncpy(tmppath, where, 1024 - ustrlen(tmppath));
diff --git a/usr.bin/doscmd/cwd.h b/usr.bin/doscmd/cwd.h
index 4e61558aef08..16c74740beb1 100644
--- a/usr.bin/doscmd/cwd.h
+++ b/usr.bin/doscmd/cwd.h
@@ -45,9 +45,9 @@ ustrcat(u_char *s1, u_char *s2)
 }
 
 static inline u_char *
-ustrncat(u_char *s1, u_char *s2, size_t n)
+ustrncat(u_char *s1, const u_char *s2, size_t n)
 {
-    return((u_char *)strncat((char *)s1, (char *)s2, n));
+    return((u_char *)strncat((char *)s1, (const char *)s2, n));
 }
 
 static inline u_char *
@@ -63,15 +63,15 @@ ustrcmp(u_char *s1, u_char *s2)
 }
 
 static inline int
-ustrncmp(u_char *s1, u_char *s2, size_t n)
+ustrncmp(const u_char *s1, const u_char *s2, size_t n)
 {
-    return(strncmp((char *)s1, (char *)s2, n));
+    return(strncmp((const char *)s1, (const char *)s2, n));
 }
 
 static inline int
-ustrlen(u_char *s)
+ustrlen(const u_char *s)
 {
-    return(strlen((char *)s));
+    return(strlen((const char *)s));
 }
 
 static inline u_char *
@@ -81,9 +81,9 @@ ustrrchr(u_char *s, u_char c)
 }
 
 static inline u_char *
-ustrdup(u_char *s)
+ustrdup(const u_char *s)
 {
-    return((u_char *)strdup((char *)s));
+    return((u_char *)strdup((const char *)s));
 }
 
 static inline int
@@ -98,7 +98,7 @@ uaccess(u_char *s, int mode)
     return(access((char *)s, mode));
 }
 
-extern void	init_path(int, u_char *, u_char *);
+extern void	init_path(int, const u_char *, const u_char *);
 extern void	dos_makereadonly(int);
 extern int	dos_readonly(int);
 extern u_char	*dos_getcwd(int);
diff --git a/usr.bin/doscmd/dos.c b/usr.bin/doscmd/dos.c
index 975c3b8f2e77..90b0b1232910 100644
--- a/usr.bin/doscmd/dos.c
+++ b/usr.bin/doscmd/dos.c
@@ -1800,7 +1800,7 @@ int21_57_0(regcontext_t *REGS)
 ** set mtime for handle
 */
 static int
-int21_57_1(regcontext_t *REGS)
+int21_57_1(regcontext_t *REGS __unused)
 {
 #ifdef __NetBSD__	/* XXX need futimes() */
 	struct stat sb;
diff --git a/usr.bin/doscmd/doscmd.c b/usr.bin/doscmd/doscmd.c
index f750b81ec74d..cec22eedc430 100644
--- a/usr.bin/doscmd/doscmd.c
+++ b/usr.bin/doscmd/doscmd.c
@@ -399,7 +399,7 @@ setup_command(int argc, char *argv[], regcontext_t *REGS)
 	p = getcwd(buffer, sizeof(buffer));
 	if (!p || !*p) p = getenv("PWD");
 	if (!p || !*p) p = "/";
-	init_path(drlton('C'), (u_char *)"/", (u_char *)p);
+	init_path(drlton('C'), "/", p);
 
 	/* look for PATH= already set, learn from it if possible */
 	for (i = 0; i < ecnt; ++i) {
@@ -451,7 +451,7 @@ setup_command(int argc, char *argv[], regcontext_t *REGS)
 
     /* XXX ??? */
     if (dos_getcwd(drlton('R')) == NULL)
-	init_path(drlton('R'), (u_char *)"/", 0);
+	init_path(drlton('R'), "/", 0);
 
     /* get program name */
     strncpy(prog, *argv++, sizeof(prog) -1);
diff --git a/usr.bin/doscmd/ems.c b/usr.bin/doscmd/ems.c
index 2ff21b0763a3..72065f7bfc98 100644
--- a/usr.bin/doscmd/ems.c
+++ b/usr.bin/doscmd/ems.c
@@ -1506,7 +1506,7 @@ check_saved_context(EMScontext *emp)
  */
 static int
 check_alloc_pages(u_short handle, u_short firstpage, u_short offset, 
-                  u_long length)
+                  u_long length __unused)
 {
     u_long nbytes;
 
diff --git a/usr.bin/doscmd/exe.c b/usr.bin/doscmd/exe.c
index 8e6172bb4a68..27ee694acba0 100644
--- a/usr.bin/doscmd/exe.c
+++ b/usr.bin/doscmd/exe.c
@@ -120,7 +120,7 @@ load_com(int fd, int start_segment)
 }
 
 static void
-load_exe(int fd, int start_segment, int reloc_segment, struct exehdr *hdr, int text_size)
+load_exe(int fd, int start_segment, int reloc_segment __unused, struct exehdr *hdr, int text_size)
 {
     char *start_addr;
     int reloc_size;
diff --git a/usr.bin/doscmd/i386-pinsn.c b/usr.bin/doscmd/i386-pinsn.c
index 5a7eff712ca6..8b20fac06429 100644
--- a/usr.bin/doscmd/i386-pinsn.c
+++ b/usr.bin/doscmd/i386-pinsn.c
@@ -1465,13 +1465,13 @@ dofloat ()
 }
 
 static void
-OP_ST(int dummy)
+OP_ST(int dummy __unused)
 {
   oappend ("%st");
 }
 
 static void
-OP_STi(int dummy)
+OP_STi(int dummy __unused)
 {
   sprintf (scratchbuf, "%%st(%d)", rm);
   oappend (scratchbuf);
@@ -1834,7 +1834,7 @@ append_pc(unsigned long pc)
 }
 
 static void
-OP_SEG(int dummy)
+OP_SEG(int dummy __unused)
 {
   static const char *sreg[] = {
     "%es","%cs","%ss","%ds","%fs","%gs","%?","%?",
@@ -1880,7 +1880,7 @@ OP_DIR(int size)
 }
 
 static void
-OP_OFF(int dummy)
+OP_OFF(int dummy __unused)
 {
   int off;
   
@@ -1894,7 +1894,7 @@ OP_OFF(int dummy)
 }
 
 static void
-OP_ESDI(int dummy)
+OP_ESDI(int dummy __unused)
 {
   oappend ("%es:(");
   oappend (aflag ? "%edi" : "%di");
@@ -1902,7 +1902,7 @@ OP_ESDI(int dummy)
 }
 
 static void
-OP_DSSI(int dummy)
+OP_DSSI(int dummy __unused)
 {
   oappend ("%ds:(");
   oappend (aflag ? "%esi" : "%si");
@@ -1910,7 +1910,7 @@ OP_DSSI(int dummy)
 }
 
 static void
-OP_C(int dummy)
+OP_C(int dummy __unused)
 {
   codep++; /* skip mod/rm */
   sprintf (scratchbuf, "%%cr%d", reg);
@@ -1918,7 +1918,7 @@ OP_C(int dummy)
 }
 
 static void
-OP_D(int dummy)
+OP_D(int dummy __unused)
 {
   codep++; /* skip mod/rm */
   sprintf (scratchbuf, "%%db%d", reg);
@@ -1926,7 +1926,7 @@ OP_D(int dummy)
 }
 
 static void
-OP_T(int dummy)
+OP_T(int dummy __unused)
 {
   codep++; /* skip mod/rm */
   sprintf (scratchbuf, "%%tr%d", reg);
diff --git a/usr.bin/doscmd/int13.c b/usr.bin/doscmd/int13.c
index e10bf5181e8a..039a6414de7b 100644
--- a/usr.bin/doscmd/int13.c
+++ b/usr.bin/doscmd/int13.c
@@ -244,7 +244,7 @@ init_hdisk(int drive, int cyl, int head, int tracksize, char *file, char *fake_p
 
     	for (fd = 0; fd < 4; ++fd) {
 	    if (*(u_short *)(di->sector0 + 0x1FE) == 0xAA55 &&
-	        ptab[fd].numSectors == head * tracksize * cyl &&
+	        ptab[fd].numSectors == (u_long)(head * tracksize * cyl) &&
 		(ptab[fd].systemID == 1 || ptab[fd].systemID == 4 ||
 		 ptab[fd].systemID == 6))
 		    break;
diff --git a/usr.bin/doscmd/intff.c b/usr.bin/doscmd/intff.c
index 7e608cf43e4c..5586c4ea1e72 100644
--- a/usr.bin/doscmd/intff.c
+++ b/usr.bin/doscmd/intff.c
@@ -139,7 +139,7 @@ int2f11_dirfn(regcontext_t *REGS)
 ** Close
 */
 static int
-int2f11_close(regcontext_t *REGS)
+int2f11_close(regcontext_t *REGS __unused)
 {
     int		fd;
 
@@ -162,7 +162,7 @@ int2f11_close(regcontext_t *REGS)
 ** read/write
 */
 static int
-int2f11_rdwr(regcontext_t *REGS)
+int2f11_rdwr(regcontext_t *REGS __unused)
 {
     int		fd;
     char	*addr;
@@ -207,7 +207,7 @@ int2f11_rdwr(regcontext_t *REGS)
 ** Get free space (like 21:36)
 */
 static int
-int2f11_free(regcontext_t *REGS)
+int2f11_free(regcontext_t *REGS __unused)
 {
     fsstat_t	fs;
     int		error;
@@ -228,7 +228,7 @@ int2f11_free(regcontext_t *REGS)
 ** get size and mode
 */
 static int
-int2f11_stat(regcontext_t *REGS)
+int2f11_stat(regcontext_t *REGS __unused)
 {
     char	fname[PATH_MAX];
     struct stat	sb;
@@ -421,7 +421,7 @@ int2f11_open(regcontext_t *REGS)
 ** find first
 */
 static int
-int2f11_findfirst(regcontext_t *REGS)
+int2f11_findfirst(regcontext_t *REGS __unused)
 {
     return(find_first(sda->filename1,sda->attrmask,
 		      (dosdir_t *)sda->foundentry,
@@ -434,7 +434,7 @@ int2f11_findfirst(regcontext_t *REGS)
 ** find next
 */
 static int
-int2f11_findnext(regcontext_t *REGS)
+int2f11_findnext(regcontext_t *REGS __unused)
 {
     return(find_next((dosdir_t *)sda->foundentry,
 		     (find_block_t *)sda->findfirst));
@@ -477,7 +477,8 @@ static int
 int2f11_fnqual(regcontext_t *REGS)
 {
     char	*fname;
-    const char	*tname;
+    char	*tname;
+    static char errmsg[] = "(failed)";
     int		savedrive;
     int		error;
 
@@ -490,7 +491,7 @@ int2f11_fnqual(regcontext_t *REGS)
     
     error = dos_makepath(fname, tname);
     if (error)
-	tname = "(failed)";
+	tname = errmsg;
 
     diskdrive = savedrive;		/* restore correct drive */
     
@@ -504,7 +505,7 @@ int2f11_fnqual(regcontext_t *REGS)
 ** Null function - we know about it but do nothing
 */
 static int
-int2f11_NULLFUNC(regcontext_t *REGS)
+int2f11_NULLFUNC(regcontext_t *REGS __unused)
 {
     return(0);
 }
@@ -515,7 +516,7 @@ int2f11_NULLFUNC(regcontext_t *REGS)
 ** no function - not handled here (error)
 */
 static int
-int2f11_NOFUNC(regcontext_t *REGS)
+int2f11_NOFUNC(regcontext_t *REGS __unused)
 {
     return(-1);
 }
diff --git a/usr.bin/doscmd/port.c b/usr.bin/doscmd/port.c
index 5fcd3a109829..9b26836fd860 100644
--- a/usr.bin/doscmd/port.c
+++ b/usr.bin/doscmd/port.c
@@ -178,7 +178,7 @@ inb_port(int port)
  */
 
 static void
-outb_nullport(int port, unsigned char byte)
+outb_nullport(int port __unused, unsigned char byte __unused)
 {
 /*
     debug(D_PORT, "outb_nullport called for port 0x%03X = 0x%02X.\n",
@@ -187,7 +187,7 @@ outb_nullport(int port, unsigned char byte)
 }
 
 static unsigned char
-inb_nullport(int port)
+inb_nullport(int port __unused)
 {
 /*
     debug(D_PORT, "inb_nullport called for port 0x%03X.\n", port);
@@ -405,7 +405,7 @@ int sound_on = 1;
 int sound_freq = 1000;
 
 void
-outb_speaker(int port, unsigned char byte)
+outb_speaker(int port __unused, unsigned char byte)
 {
 #if 0 /*XXXXX*/
     if (raw_kbd) {
@@ -420,7 +420,7 @@ outb_speaker(int port, unsigned char byte)
 }
 
 unsigned char
-inb_speaker(int port)
+inb_speaker(int port __unused)
 {
 /*    port_61 = (port_61 + 1) & 0xff; */
     return(port_61);
diff --git a/usr.bin/doscmd/signal.c b/usr.bin/doscmd/signal.c
index 11f669b59033..b0de9b95c205 100644
--- a/usr.bin/doscmd/signal.c
+++ b/usr.bin/doscmd/signal.c
@@ -44,7 +44,7 @@ regcontext_t *saved_regcontext;
 int		saved_valid = 0; 
 
 static void
-sanity_check(struct sigframe *sf)
+sanity_check(struct sigframe *sf __unused)
 {
 #if 0
     static sigset_t oset;
diff --git a/usr.bin/doscmd/timer.c b/usr.bin/doscmd/timer.c
index 29a69151a6c4..d2eec93a646b 100644
--- a/usr.bin/doscmd/timer.c
+++ b/usr.bin/doscmd/timer.c
@@ -6,7 +6,7 @@
 #include "doscmd.h"
 
 static void
-int08(regcontext_t *REGS)
+int08(regcontext_t *REGS __unused)
 {
     *(u_long *)&BIOSDATA[0x6c] += 1;    /* ticks since midnight */
     while (*(u_long *)&BIOSDATA[0x6c] >= 24*60*6*182) {
@@ -19,14 +19,14 @@ int08(regcontext_t *REGS)
 }
 
 static void
-int1c(regcontext_t *REGS)
+int1c(regcontext_t *REGS __unused)
 {
 }
 
 unsigned char timer;
 
 static u_char
-inb_timer(int port)
+inb_timer(int port __unused)
 {
     return (--timer);
 }
diff --git a/usr.bin/doscmd/tty.c b/usr.bin/doscmd/tty.c
index 41e9792a2523..2a2ae3938621 100644
--- a/usr.bin/doscmd/tty.c
+++ b/usr.bin/doscmd/tty.c
@@ -198,7 +198,7 @@ static void	vram2ximage(void);
 #define	K4_ERROR	0x80
 
 static void
-Failure(void *arg)
+Failure(void *arg __unused)
 {
         fprintf(stderr, "X Connection shutdown\n");
 	quit(1);
@@ -234,7 +234,7 @@ console_denit(void *arg)
 }
 
 void
-_kbd_event(int fd, int cond, void *arg, regcontext_t *REGS)
+_kbd_event(int fd, int cond, void *arg __unused, regcontext_t *REGS __unused)
 {
     if (!(cond & AS_RD))
 	return;
@@ -352,7 +352,7 @@ setgc(u_short attr)
 }
 
 void
-video_update(regcontext_t *REGS)
+video_update(regcontext_t *REGS __unused)
 {
 #ifndef NO_X
 	static int icnt = 3;
@@ -769,7 +769,7 @@ debug_event(int fd, int cond, void *arg, regcontext_t *REGS)
 }
 
 unsigned char
-inb_port60(int port)
+inb_port60(int port __unused)
 {       
     int r = break_code;
     break_code = 0;
@@ -791,7 +791,7 @@ kbd_event(int fd, int cond, void *arg, regcontext_t *REGS)
 }
 
 void
-int09(REGISTERS)
+int09(REGISTERS __unused)
 {
     if (raw_kbd) {
 	if (scan_code != 0xffff) {
@@ -2210,7 +2210,7 @@ update_pixels()
 }
 
 void
-write_vram(void *arg)
+write_vram(void *arg __unused)
 {
     int fd;
 
diff --git a/usr.bin/du/Makefile b/usr.bin/du/Makefile
index 863e3921f58a..d279a9702ca2 100644
--- a/usr.bin/du/Makefile
+++ b/usr.bin/du/Makefile
@@ -2,7 +2,7 @@
 # $FreeBSD$
 
 PROG=	du
-CFLAGS+= -Wall
+WARNS?=	2
 DPADD=	${LIBM}
 LDADD=	-lm
 
diff --git a/usr.bin/du/du.c b/usr.bin/du/du.c
index 85953418fbed..9d44963af464 100644
--- a/usr.bin/du/du.c
+++ b/usr.bin/du/du.c
@@ -117,6 +117,7 @@ main(argc, argv)
 	int		depth;
 	int		Hflag, Lflag, Pflag, aflag, sflag, dflag, cflag, hflag, ch, notused, rval;
 	char 		**save;
+	static char	dot[] = ".";
 
 	Hflag = Lflag = Pflag = aflag = sflag = dflag = cflag = hflag = 0;
 	
@@ -225,7 +226,7 @@ main(argc, argv)
 
 	if (!*argv) {
 		argv = save;
-		argv[0] = ".";
+		argv[0] = dot;
 		argv[1] = NULL;
 	}