diff --git a/sys/src/9/ip/devip.c b/sys/src/9/ip/devip.c
index 0437d59ed..2629c02ef 100644
--- a/sys/src/9/ip/devip.c
+++ b/sys/src/9/ip/devip.c
@@ -277,12 +277,12 @@ newipaux(char *owner, char *tag)
 static Chan*
 ipattach(char* spec)
 {
-	ulong dev;
 	Chan *c;
+	ulong dev;
 
-	dev = strtoul(spec, nil, 0);
+	dev = strtoul(spec, nil, 10);
 	if(dev >= Nfs)
-		error(Ebadspec);
+		error(Enodev);
 
 	qlock(&fslock);
 	if(ipfs[dev] == nil){
diff --git a/sys/src/9/pc/devvga.c b/sys/src/9/pc/devvga.c
index 77048bf06..ab307f9fb 100644
--- a/sys/src/9/pc/devvga.c
+++ b/sys/src/9/pc/devvga.c
@@ -90,7 +90,7 @@ static Chan*
 vgaattach(char* spec)
 {
 	if(*spec && strcmp(spec, "0"))
-		error(Eio);
+		error(Enodev);
 	return devattach('v', spec);
 }
 
diff --git a/sys/src/9/port/devaudio.c b/sys/src/9/port/devaudio.c
index bb25df736..9201efc55 100644
--- a/sys/src/9/port/devaudio.c
+++ b/sys/src/9/port/devaudio.c
@@ -120,16 +120,13 @@ audioclone(Chan *c, Audio *adev)
 static Chan*
 audioattach(char *spec)
 {
-	static int attached = 0;
+	static ulong attached = 0;
 	Audiochan *ac;
 	Audio *adev;
 	Chan *c;
-	int i;
+	ulong i;
 
-	if(spec != nil && *spec != '\0')
-		i = strtol(spec, 0, 10);
-	else
-		i = 0;
+	i = strtoul(spec, nil, 10);
 	for(adev = audiodevs; adev; adev = adev->next)
 		if(adev->ctlrno == i)
 			break;
diff --git a/sys/src/9/port/devbridge.c b/sys/src/9/port/devbridge.c
index 805751aee..bc4537270 100644
--- a/sys/src/9/port/devbridge.c
+++ b/sys/src/9/port/devbridge.c
@@ -193,14 +193,14 @@ bridgeinit(void)
 }
 
 static Chan*
-bridgeattach(char* spec)
+bridgeattach(char *spec)
 {
 	Chan *c;
-	int dev;
+	ulong dev;
 
-	dev = atoi(spec);
-	if(dev<0 || dev >= Maxbridge)
-		error("bad specification");
+	dev = strtoul(spec, nil, 10);
+	if(dev >= Maxbridge)
+		error(Enodev);
 
 	c = devattach('B', spec);
 	mkqid(&c->qid, QID(0, Qtopdir), 0, QTDIR);
diff --git a/sys/src/9/port/devether.c b/sys/src/9/port/devether.c
index abc56f325..bff515611 100644
--- a/sys/src/9/port/devether.c
+++ b/sys/src/9/port/devether.c
@@ -25,7 +25,7 @@ etherattach(char* spec)
 
 	ctlrno = 0;
 	if(*spec){
-		ctlrno = strtoul(spec, &conf, 0);
+		ctlrno = strtoul(spec, &conf, 10);
 		if(ctlrno >= MaxEther)
 			error(Enodev);
 		if(conf == spec)
diff --git a/sys/src/9/port/devflash.c b/sys/src/9/port/devflash.c
index 80a115424..49fa8c9ac 100644
--- a/sys/src/9/port/devflash.c
+++ b/sys/src/9/port/devflash.c
@@ -167,11 +167,11 @@ static Chan*
 flashattach(char *spec)
 {
 	Flash *f;
-	int bank;
 	Chan *c;
+	ulong bank;
 
-	bank = strtol(spec, nil, 0);
-	if(bank < 0 || bank >= Nbanks ||
+	bank = strtoul(spec, nil, 10);
+	if(bank >= Nbanks ||
 	   (f = flash.card[bank]) == nil ||
 	   f->attach != nil && f->attach(f) < 0)
 		error(Enodev);
diff --git a/sys/src/9/port/devloopback.c b/sys/src/9/port/devloopback.c
index 76f37890a..c251387a3 100644
--- a/sys/src/9/port/devloopback.c
+++ b/sys/src/9/port/devloopback.c
@@ -121,14 +121,11 @@ loopbackattach(char *spec)
 	Queue *q;
 	Chan *c;
 	int chan;
-	int dev;
+	ulong dev;
 
-	dev = 0;
-	if(spec != nil){
-		dev = atoi(spec);
-		if(dev >= Nloopbacks)
-			error(Ebadspec);
-	}
+	dev = strtoul(spec, nil, 10);
+	if(dev >= Nloopbacks)
+		error(Enodev);
 
 	c = devattach('X', spec);
 	if(waserror()){
diff --git a/sys/src/9/port/devsd.c b/sys/src/9/port/devsd.c
index 5ea1d47b8..32d6f26a1 100644
--- a/sys/src/9/port/devsd.c
+++ b/sys/src/9/port/devsd.c
@@ -662,8 +662,8 @@ sdattach(char* spec)
 	if(spec[0] != 's' || spec[1] != 'd')
 		error(Ebadspec);
 	idno = spec[2];
-	subno = strtol(&spec[3], &p, 0);
-	if(p == &spec[3])
+	subno = strtol(&spec[3], &p, 10);
+	if(subno < 0 || p == &spec[3])
 		error(Ebadspec);
 
 	if((sdev=sdgetdev(idno)) == nil)
diff --git a/sys/src/9/port/devsdp.c b/sys/src/9/port/devsdp.c
index a840bc635..5d52fdb9d 100644
--- a/sys/src/9/port/devsdp.c
+++ b/sys/src/9/port/devsdp.c
@@ -364,14 +364,14 @@ static Chan*
 sdpattach(char* spec)
 {
 	Chan *c;
-	int dev;
 	char buf[100];
 	Sdp *sdp;
 	int start;
+	ulong dev;
 
-	dev = atoi(spec);
-	if(dev<0 || dev >= Nfs)
-		error("bad specification");
+	dev = strtoul(spec, nil, 10);
+	if(dev >= Nfs)
+		error(Enodev);
 
 	c = devattach('E', spec);
 	c->qid = (Qid){QID(0, Qtopdir), 0, QTDIR};
@@ -384,7 +384,7 @@ sdpattach(char* spec)
 	qunlock(sdp);
 
 	if(start) {
-		snprint(buf, sizeof(buf), "sdpackproc%d", dev);
+		snprint(buf, sizeof(buf), "sdpackproc%lud", dev);
 		kproc(buf, sdpackproc, sdp);
 	}