diff --git a/bin/ls/ls.c b/bin/ls/ls.c
index 604d4ad..3a758bd 100644
--- a/bin/ls/ls.c
+++ b/bin/ls/ls.c
@@ -139,6 +139,7 @@ main(int argc, char *argv[])
 	struct winsize win;
 	int ch, fts_options, notused;
 	char *p;
+        const char *errstr = NULL;
 #ifdef COLORLS
 	char termcapbuf[1024];	/* termcap definition buffer */
 	char tcapbuf[512];	/* capability buffer */
@@ -150,9 +151,11 @@ main(int argc, char *argv[])
 	/* Terminal defaults to -Cq, non-terminal defaults to -1. */
 	if (isatty(STDOUT_FILENO)) {
 		termwidth = 80;
-		if ((p = getenv("COLUMNS")) != NULL && *p != '\0')
-			termwidth = atoi(p);
-		else if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) != -1 &&
+		if ((p = getenv("COLUMNS")) != NULL && *p != '\0') {
+			termwidth = strtonum(p, 0, INT_MAX, &errstr);
+			if (errstr)
+				termwidth = 80;
+		} else if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) != -1 &&
 		    win.ws_col > 0)
 			termwidth = win.ws_col;
 		f_nonprint = 1;
@@ -160,8 +163,11 @@ main(int argc, char *argv[])
 		f_singlecol = 1;
 		/* retrieve environment variable, in case of explicit -C */
 		p = getenv("COLUMNS");
-		if (p)
-			termwidth = atoi(p);
+		if (p) {
+			termwidth = strtonum(p, 0, INT_MAX, &errstr);
+			if (errstr)
+				termwidth = 80;
+                }
 	}
 
 	/*
diff --git a/bin/pax/options.c b/bin/pax/options.c
index 4cf4ebf..cf29369 100644
--- a/bin/pax/options.c
+++ b/bin/pax/options.c
@@ -179,6 +179,7 @@ pax_options(int argc, char **argv)
 	unsigned int flg = 0;
 	unsigned int bflg = 0;
 	char *pt;
+	const char *errstr = NULL;
 	FSUB tmp;
 
 	/*
@@ -407,9 +408,12 @@ pax_options(int argc, char **argv)
 			flg |= CEF;
 			if (strcmp(NONE, optarg) == 0)
 				maxflt = -1;
-			else if ((maxflt = atoi(optarg)) < 0) {
-				paxwarn(1, "Error count value must be positive");
-				pax_usage();
+			else {
+				maxflt = strtonum(optarg, 0, INT_MAX, &errstr);
+				if (errstr) {
+					paxwarn(1, "Error count value : %s", errstr);
+					pax_usage();
+				}
 			}
 			break;
 		case 'G':
@@ -1013,6 +1017,7 @@ cpio_options(int argc, char **argv)
 {
 	int c, i;
 	char *str;
+	const char *errstr = NULL;
 	FSUB tmp;
 	FILE *fp;
 
@@ -1140,7 +1145,11 @@ cpio_options(int argc, char **argv)
 				/*
 				 * set block size in bytes
 				 */
-				wrblksz = atoi(optarg);
+				wrblksz = strtonum(optarg, 0, INT_MAX, &errstr);
+				if (errstr) {
+					paxwarn(1, "Error byte size : %s", errstr);
+					pax_usage();
+				}
 				break;
 			case 'E':
 				/*
diff --git a/contrib/nvi/cl/cl_term.c b/contrib/nvi/cl/cl_term.c
index d851930..9b489d2 100644
--- a/contrib/nvi/cl/cl_term.c
+++ b/contrib/nvi/cl/cl_term.c
@@ -356,6 +356,7 @@ cl_ssize(SCR *sp, int sigwinch, size_t *rowp, size_t *colp, int *changedp)
 	size_t col, row;
 	int rval;
 	char *p;
+        char *rowptr = NULL, *colptr = NULL;
 
 	/* Assume it's changed. */
 	if (changedp != NULL)
@@ -447,10 +448,15 @@ noterm:	if (row == 0)
 	 * deleting the LINES and COLUMNS environment variables from their
 	 * dot-files.
 	 */
-	if ((p = getenv("LINES")) != NULL)
-		row = strtol(p, NULL, 10);
-	if ((p = getenv("COLUMNS")) != NULL)
-		col = strtol(p, NULL, 10);
+	if ((p = getenv("LINES")) != NULL) {
+		row = strtol(p, &rowptr, 10);
+		if (errno == ERANGE || *rowptr != '\0')
+ 			row = 24;
+	} if ((p = getenv("COLUMNS")) != NULL) {
+		col = strtol(p, &colptr, 10);
+		if (errno == ERANGE || *colptr != '\0')
+ 			col = 80;
+        }
 
 	if (rowp != NULL)
 		*rowp = row;
diff --git a/sbin/camcontrol/camcontrol.c b/sbin/camcontrol/camcontrol.c
index 19268c6..0759e24 100644
--- a/sbin/camcontrol/camcontrol.c
+++ b/sbin/camcontrol/camcontrol.c
@@ -2995,14 +2995,20 @@ scsiformat(struct cam_device *device, int argc, char **argv,
 	 && (timeout == 0)) {
 		char str[1024];
 		int new_timeout = 0;
+		const char *errstr = NULL;
 
 		fprintf(stdout, "Enter new timeout in seconds or press\n"
 			"return to keep the current timeout [%d] ",
 			use_timeout / 1000);
 
 		if (fgets(str, sizeof(str), stdin) != NULL) {
-			if (str[0] != '\0')
-				new_timeout = atoi(str);
+			if (str[0] != '\0') {
+				new_timeout = strtonum(str, 0, INT_MAX, &errstr);
+				if (errstr) {
+					fprintf(stderr, "Invalid new timeout %s\n", errstr);
+					goto scsiformat_bailout;
+				}
+			}
 		}
 
 		if (new_timeout != 0) {
diff --git a/sbin/comcontrol/comcontrol.c b/sbin/comcontrol/comcontrol.c
index 561131f..644e9b6 100644
--- a/sbin/comcontrol/comcontrol.c
+++ b/sbin/comcontrol/comcontrol.c
@@ -96,14 +96,18 @@ main(int argc, char *argv[])
 					usage();
 				if (argv[3] == NULL || !isdigit(argv[3][0]))
 					usage();
-				dtrwait = atoi(argv[3]);
+				dtrwait = strtol(argv[3], NULL, 10);
+				if (errno == ERANGE)
+					usage();
 				argv += 2;
 			} else if (strcmp(argv[2],"drainwait") == 0) {
 				if (drainwait >= 0)
 					usage();
 				if (argv[3] == NULL || !isdigit(argv[3][0]))
 					usage();
-				drainwait = atoi(argv[3]);
+				drainwait = strtol(argv[3], NULL, 10);
+				if (errno == ERANGE)
+					usage();
 				argv += 2;
 			} else {
 				usage();
diff --git a/sbin/fsdb/fsdbutil.c b/sbin/fsdb/fsdbutil.c
index 8ea6f83..6ec3595 100644
--- a/sbin/fsdb/fsdbutil.c
+++ b/sbin/fsdb/fsdbutil.c
@@ -37,6 +37,7 @@
 #include <pwd.h>
 #include <string.h>
 #include <time.h>
+#include <errno.h>
 
 #include <vfs/ufs/dinode.h>
 #include <vfs/ufs/fs.h>
@@ -158,13 +159,17 @@ charsperline(void)
 {
 	int columns;
 	char *cp;
+	char *p = NULL;
 	struct winsize ws;
 
 	columns = 0;
 	if (ioctl(0, TIOCGWINSZ, &ws) != -1)
 		columns = ws.ws_col;
-	if (columns == 0 && (cp = getenv("COLUMNS")))
-		columns = atoi(cp);
+	if (columns == 0 && (cp = getenv("COLUMNS"))) {
+		columns = strtol(cp, &p, 10);
+		if (errno == ERANGE || *p != '\0')
+			columns = 80;
+	}
 	if (columns == 0)
 		columns = 80;	/* last resort */
 	return (columns);
diff --git a/sbin/growfs/growfs.c b/sbin/growfs/growfs.c
index bda65fe..7f31176 100644
--- a/sbin/growfs/growfs.c
+++ b/sbin/growfs/growfs.c
@@ -55,6 +55,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 #include <vfs/ufs/dinode.h>
 #include <vfs/ufs/fs.h>
 
@@ -1869,6 +1870,7 @@ charsperline(void)
 {
 	int	columns;
 	char	*cp;
+	char	*p = NULL;
 	struct winsize	ws;
 
 	DBG_ENTER;
@@ -1878,7 +1880,9 @@ charsperline(void)
 		columns = ws.ws_col;
 	}
 	if (columns == 0 && (cp = getenv("COLUMNS"))) {
-		columns = atoi(cp);
+		columns = strtol(cp, &p, 10);
+		if (errno == ERANGE || *p != '\0')
+			columns = 80;
 	}
 	if (columns == 0) {
 		columns = 80;	/* last resort */
diff --git a/sbin/ifconfig/ifcarp.c b/sbin/ifconfig/ifcarp.c
index abb2ae1..4046de4 100644
--- a/sbin/ifconfig/ifcarp.c
+++ b/sbin/ifconfig/ifcarp.c
@@ -119,11 +119,12 @@ setcarp_vhid(const char *val, int d, int s, const struct afswtch *afp)
 {
 	int vhid;
 	struct carpreq carpr;
+	const char *errstr = NULL;
 
-	vhid = atoi(val);
+	vhid = strtonum(val, 1, INT_MAX, &errstr);
 
-	if (vhid <= 0)
-		errx(1, "vhid must be greater than 0");
+	if (errstr)
+		errx(1, "invalid vhid : %s", errstr);
 
 	memset((char *)&carpr, 0, sizeof(struct carpreq));
 	ifr.ifr_data = (caddr_t)&carpr;
@@ -142,8 +143,11 @@ setcarp_advskew(const char *val, int d, int s, const struct afswtch *afp)
 {
 	int advskew;
 	struct carpreq carpr;
+	const char *errstr = NULL;
 
-	advskew = atoi(val);
+	advskew = strtonum(val, 1, 255, &errstr);
+	if (errstr)
+		errx(1, "invalid advskew value : %s", errstr);
 
 	memset((char *)&carpr, 0, sizeof(struct carpreq));
 	ifr.ifr_data = (caddr_t)&carpr;
@@ -162,8 +166,11 @@ setcarp_advbase(const char *val, int d, int s, const struct afswtch *afp)
 {
 	int advbase;
 	struct carpreq carpr;
+	const char *errstr = NULL;
 
-	advbase = atoi(val);
+	advbase = strtonum(val, 1, 254, &errstr);
+	if (errstr)
+		errx(1, "invalid advbase value : %s", errstr);
 
 	memset((char *)&carpr, 0, sizeof(struct carpreq));
 	ifr.ifr_data = (caddr_t)&carpr;
diff --git a/sbin/ifconfig/ifconfig.c b/sbin/ifconfig/ifconfig.c
index 0e9363d..c5d2bf8 100644
--- a/sbin/ifconfig/ifconfig.c
+++ b/sbin/ifconfig/ifconfig.c
@@ -779,9 +779,12 @@ static void
 setifmetric(const char *val, int dummy __unused, int s, 
     const struct afswtch *afp)
 {
+	const char *errstr = NULL;
 	strncpy(ifr.ifr_name, name, sizeof (ifr.ifr_name));
-	ifr.ifr_metric = atoi(val);
-	if (ioctl(s, SIOCSIFMETRIC, (caddr_t)&ifr) < 0)
+	ifr.ifr_metric = strtonum(val, 0, INT_MAX, &errstr);
+	if (errstr)
+		warn("invalid metric value %s", errstr);
+	else if (ioctl(s, SIOCSIFMETRIC, (caddr_t)&ifr) < 0)
 		warn("ioctl (set metric)");
 }
 
@@ -789,9 +792,12 @@ static void
 setifmtu(const char *val, int dummy __unused, int s, 
     const struct afswtch *afp)
 {
+	const char *errstr = NULL;
 	strncpy(ifr.ifr_name, name, sizeof (ifr.ifr_name));
-	ifr.ifr_mtu = atoi(val);
-	if (ioctl(s, SIOCSIFMTU, (caddr_t)&ifr) < 0)
+	ifr.ifr_mtu = strtonum(val, 0, INT_MAX, &errstr);
+	if (errstr)
+		warn("invalid mtu value %s", errstr);
+	else if (ioctl(s, SIOCSIFMTU, (caddr_t)&ifr) < 0)
 		warn("ioctl (set mtu)");
 }
 
@@ -799,9 +805,12 @@ static void
 setiftsolen(const char *val, int dummy __unused, int s,
     const struct afswtch *afp)
 {
+	const char *errstr = NULL;
 	strncpy(ifr.ifr_name, name, sizeof (ifr.ifr_name));
-	ifr.ifr_tsolen = atoi(val);
-	if (ioctl(s, SIOCSIFTSOLEN, (caddr_t)&ifr) < 0)
+	ifr.ifr_tsolen = strtonum(val, 0, INT_MAX, &errstr);
+	if (errstr)
+		warn("invalid tsolen value %s", errstr);
+	else if (ioctl(s, SIOCSIFTSOLEN, (caddr_t)&ifr) < 0)
 		warn("ioctl (set tsolen)");
 }
 
diff --git a/sbin/ifconfig/ifieee80211.c b/sbin/ifconfig/ifieee80211.c
index e0e890b..1e37fe2 100644
--- a/sbin/ifconfig/ifieee80211.c
+++ b/sbin/ifconfig/ifieee80211.c
@@ -1848,13 +1848,13 @@ DECL_CMD_FUNC(set80211meshttl, val, d)
 static
 DECL_CMD_FUNC(set80211meshforward, val, d)
 {
-	set80211(s, IEEE80211_IOC_MESH_FWRD, atoi(val), 0, NULL);
+	set80211(s, IEEE80211_IOC_MESH_FWRD, d, 0, NULL);
 }
 
 static
 DECL_CMD_FUNC(set80211meshpeering, val, d)
 {
-	set80211(s, IEEE80211_IOC_MESH_AP, atoi(val), 0, NULL);
+	set80211(s, IEEE80211_IOC_MESH_AP, d, 0, NULL);
 }
 
 static
diff --git a/sbin/route/route.c b/sbin/route/route.c
index 924c764..e289b92 100644
--- a/sbin/route/route.c
+++ b/sbin/route/route.c
@@ -543,6 +543,7 @@ set_metric(char *value, int key)
 {
 	int flag = 0;
 	u_long noval, *valp = &noval;
+	char *p = NULL;
 
 	switch (key) {
 #define caseof(x, y, z)	case x: valp = &rt_metrics.z; flag = y; break
@@ -563,7 +564,9 @@ set_metric(char *value, int key)
 		rt_metrics.rmx_locks |= flag;
 	if (locking)
 		locking = 0;
-	*valp = atoi(value);
+	*valp = strtol(value, &p, 10);
+	if (errno == ERANGE || *p != '\0')
+		errx(EX_OSERR, "%s : bad metric", value);
 }
 
 static void
diff --git a/sbin/slattach/slattach.c b/sbin/slattach/slattach.c
index f6794b6..35978ef 100644
--- a/sbin/slattach/slattach.c
+++ b/sbin/slattach/slattach.c
@@ -45,6 +45,7 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <limits.h>
 #include <string.h>
 #include <syslog.h>
 #include <termios.h>
@@ -105,6 +106,7 @@ int
 main(int argc, char **argv)
 {
 	int option;
+	const char *errstr = NULL;
 
 	while ((option = getopt(argc, argv, "ace:fhlnr:s:u:zLK:O:S:")) != -1) {
 		switch (option) {
@@ -135,7 +137,11 @@ main(int argc, char **argv)
 			redial_cmd = (char*) strdup (optarg);
 			break;
 		case 's':
-			speed = atoi(optarg);
+			speed = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr) {
+				fprintf(stderr, "bad speed value : %s", errstr);
+				exit(1);
+			}
 			break;
 		case 'u':
 			config_cmd = (char*) strdup (optarg);
diff --git a/sbin/startslip/startslip.c b/sbin/startslip/startslip.c
index c035ec8..fb2fe94 100644
--- a/sbin/startslip/startslip.c
+++ b/sbin/startslip/startslip.c
@@ -42,6 +42,7 @@
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <limits.h>
 #include <string.h>
 #include <syslog.h>
 #include <termios.h>
@@ -115,6 +116,7 @@ main(int argc, char **argv)
 	pid_t pid;
 	struct termios t;
 	int result;
+	const char *errstr = NULL;
 
 	while ((ch = getopt(argc, argv, "dhlb:s:t:w:A:U:D:W:K:O:S:L")) != -1)
 		switch (ch) {
@@ -122,7 +124,9 @@ main(int argc, char **argv)
 			debug = 1;
 			break;
 		case 'b':
-			speed = atoi(optarg);
+			speed = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "bad speed value (%s)", errstr);
 			break;
 		case 's':
 			if (diali >= MAXDIALS)
@@ -130,10 +134,14 @@ main(int argc, char **argv)
 			dials[diali++] = strdup(optarg);
 			break;
 		case 't':
-			script_timeout = atoi(optarg);
+			script_timeout = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "bad script_timeout value (%s)", errstr);
 			break;
 		case 'w':
-			wait_time = atoi(optarg);
+			wait_time = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				errx(1, "bas wait_time value (%s)", errstr);
 			break;
 		case 'W':
 			MAXTRIES = atoi(optarg);
diff --git a/sbin/sysctl/sysctl.c b/sbin/sysctl/sysctl.c
index 14f9d89..f4acacb 100644
--- a/sbin/sysctl/sysctl.c
+++ b/sbin/sysctl/sysctl.c
@@ -208,21 +208,29 @@ parse(const char *string)
 						    (char *)newval);
 				} else
 					intval = (int) strtol(newval, NULL, 0);
+				if (errno == ERANGE)
+					errx(1, "value %s out of range", (char *)newval);
 				newval = &intval;
 				newsize = sizeof(intval);
 				break;
 			case CTLTYPE_UINT:
 				uintval = (int) strtoul(newval, NULL, 0);
+				if (errno == ERANGE)
+					errx(1, "value %s out of range", (char *)newval);
 				newval = &uintval;
 				newsize = sizeof uintval;
 				break;
 			case CTLTYPE_LONG:
 				longval = strtol(newval, NULL, 0);
+				if (errno == ERANGE)
+					errx(1, "value %s out of range", (char *)newval);
 				newval = &longval;
 				newsize = sizeof longval;
 				break;
 			case CTLTYPE_ULONG:
 				ulongval = strtoul(newval, NULL, 0);
+				if (errno == ERANGE)
+					errx(1, "value %s out of range", (char *)newval);
 				newval = &ulongval;
 				newsize = sizeof ulongval;
 				break;
diff --git a/sbin/vinum/v.c b/sbin/vinum/v.c
index 13b8de4..e08f5e8 100644
--- a/sbin/vinum/v.c
+++ b/sbin/vinum/v.c
@@ -316,6 +316,7 @@ parseline(int args, char *argv[])
     int j;
     enum keyword command;				    /* command to execute */
 
+    const char *errstr = NULL;
     if (hist != NULL) {				    /* save the command to history file */
 	timestamp();
 	for (i = 0; i < args; i++)			    /* all args */
@@ -360,10 +361,13 @@ parseline(int args, char *argv[])
 	    case 'i':					    /* interval */
 		interval = 0;
 		if (argv[i][j + 1] != '\0')		    /* operand follows, */
-		    interval = atoi(&argv[i][j + 1]);	    /* use it */
+		    interval = strtonum(&argv[i][j + 1], 0, INT_MAX, &errstr);	    /* use it */
 		else if (args > (i + 1))		    /* another following, */
-		    interval = atoi(argv[++i]);		    /* use it */
-		if (interval == 0)			    /* nothing valid, */
+		    interval = strtonum(argv[++i], 0, INT_MAX, &errstr);		    /* use it */
+		if (errstr) {
+		    fprintf(stderr, "-i: invalid interval specified: %s\n", errstr);
+		    exit(1);
+		} else if (interval == 0)			    /* nothing valid, */
 		    fprintf(stderr, "-i: no interval specified\n");
 		break;
 
@@ -387,10 +391,13 @@ parseline(int args, char *argv[])
 	    case 'S':
 		SSize = 0;
 		if (argv[i][j + 1] != '\0')		    /* operand follows, */
-		    SSize = atoi(&argv[i][j + 1]);	    /* use it */
+		    SSize = strtonum(&argv[i][j + 1], 0, INT_MAX, &errstr);	    /* use it */
 		else if (args > (i + 1))		    /* another following, */
-		    SSize = atoi(argv[++i]);		    /* use it */
-		if (SSize == 0)				    /* nothing valid, */
+		    SSize = strtonum(argv[++i], 0, INT_MAX, &errstr);		    /* use it */
+		if (errstr) {
+		    fprintf(stderr, "-S: invalid size specified %s", errstr);
+		    exit(1);
+		} else if (SSize == 0)				    /* nothing valid, */
 		    fprintf(stderr, "-S: no size specified\n");
 		break;
 
diff --git a/usr.bin/column/column.c b/usr.bin/column/column.c
index fc1345d..bad2b54 100644
--- a/usr.bin/column/column.c
+++ b/usr.bin/column/column.c
@@ -71,15 +71,18 @@ main(int argc, char **argv)
 	FILE *fp;
 	int ch, tflag, xflag;
 	char *p;
-	const char *src;
+	const char *src, *errstr = NULL;;
 	wchar_t *newsep;
 	size_t seplen;
 
 	setlocale(LC_ALL, "");
 
 	if (ioctl(1, TIOCGWINSZ, &win) == -1 || !win.ws_col) {
-		if ((p = getenv("COLUMNS")))
-			termwidth = atoi(p);
+		if ((p = getenv("COLUMNS"))) {
+			termwidth = strtonum(p, 0, INT_MAX, &errstr);
+			if (errstr)
+				termwidth = 80;
+		}
 	} else
 		termwidth = win.ws_col;
 
@@ -87,7 +90,9 @@ main(int argc, char **argv)
 	while ((ch = getopt(argc, argv, "c:s:tx")) != -1)
 		switch(ch) {
 		case 'c':
-			termwidth = atoi(optarg);
+			termwidth = strtonum(optarg, 0, INT_MAX, &errstr);
+			if (errstr)
+				termwidth = 80;
 			break;
 		case 's':
 			src = optarg;