--- /n/sources/plan9/sys/src/libmp/port/strtomp.c	Sat Jun 14 00:00:00 2025
+++ /sys/src/libmp/port/strtomp.c	Tue Jun 23 00:00:00 2026
@@ -1,6 +1,5 @@
 #include "os.h"
 #include <mp.h>
-#include <libsec.h>
 #include "dat.h"
 
 static struct {
@@ -44,21 +43,25 @@ init(void)
 }
 
 static char*
-from16(char *a, mpint *b)
+frompow2(char *a, mpint *b, int s)
 {
 	char *p, *next;
 	int i;
 	mpdigit x;
+	int sn;
 
+	sn = 1<<s;
 	for(p = a; *p; p++)
-		if(tab.t16[*(uchar*)p] == INVAL)
+		if(tab.t16[*(uchar*)p] >= sn)
 			break;
-	mpbits(b, (p-a)*4);
+
+	mpbits(b, (p-a)*s);
 	b->top = 0;
 	next = p;
+
 	while(p > a){
 		x = 0;
-		for(i = 0; i < Dbits; i += 4){
+		for(i = 0; i < Dbits; i += s){
 			if(p <= a)
 				break;
 			x |= tab.t16[*(uchar*)--p]<<i;
@@ -68,6 +71,40 @@ from16(char *a, mpint *b)
 	return next;
 }
 
+static char*
+from8(char *a, mpint *b)
+{
+	char *p, *next;
+	mpdigit x, y;
+	int i;
+
+	for(p = a; *p; p++)
+		if(tab.t10[*(uchar*)p] >= 8)
+			break;
+
+	mpbits(b, (p-a)*3);
+	b->top = 0;
+	next = p;
+
+	i = 0;
+	x = y = 0;
+	while(p > a){
+		y = tab.t10[*(uchar*)--p];
+		x |= y << i;
+		i += 3;
+		if(i >= Dbits){
+Digout:
+			i -= Dbits;
+			b->p[b->top++] = x;
+			x = y >> 3-i;
+		}
+	}
+	if(i > 0)
+		goto Digout;
+
+	return next;
+}
+
 static ulong mppow10[] = {
 	1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000
 };
@@ -111,42 +148,25 @@ from10(char *a, mpint *b)
 }
 
 static char*
-from64(char *a, mpint *b)
-{
-	char *buf = a;
-	uchar *p;
-	int n, m;
-
-	for(; tab.t64[*(uchar*)a] != INVAL; a++)
-		;
-	n = a-buf;
-	mpbits(b, n*6);
-	p = malloc(n);
-	if(p == nil)
-		return a;
-	m = dec64(p, n, buf, n);
-	betomp(p, m, b);
-	free(p);
-	return a;
-}
-
-static char*
-from32(char *a, mpint *b)
+fromdecx(char *a, mpint *b, uchar tab[256], int (*dec)(uchar*, int, char*, int))
 {
 	char *buf = a;
 	uchar *p;
 	int n, m;
 
-	for(; tab.t64[*(uchar*)a] != INVAL; a++)
+	b->top = 0;
+	for(; tab[*(uchar*)a] != INVAL; a++)
 		;
 	n = a-buf;
-	mpbits(b, n*5);
-	p = malloc(n);
-	if(p == nil)
-		return a;
-	m = dec32(p, n, buf, n);
-	betomp(p, m, b);
-	free(p);
+	if(n > 0){
+		p = malloc(n);
+		if(p == nil)
+			sysfatal("malloc: %r");
+		m = (*dec)(p, n, buf, n);
+		if(m > 0)
+			betomp(p, m, b);
+		free(p);
+	}
 	return a;
 }
 
@@ -177,29 +197,56 @@ strtomp(char *a, char **pp, int base, mpint *b)
 		break;
 	}
 
+	if(base == 0){
+		base = 10;
+		if(a[0] == '0'){
+			if(a[1] == 'x' || a[1] == 'X') {
+				a += 2;
+				base = 16;
+			} else if(a[1] == 'b' || a[1] == 'B') {
+				a += 2;
+				base = 2;
+			} else if(a[1] >= '0' && a[1] <= '7') {
+				a++;
+				base = 8;
+			}
+		}
+	}
+
 	switch(base){
+	case 2:
+		e = frompow2(a, b, 1);
+		break;
+	case 4:
+		e = frompow2(a, b, 2);
+		break;
+	case 8:
+		e = from8(a, b);
+		break;
 	case 10:
 		e = from10(a, b);
 		break;
-	default:
 	case 16:
-		e = from16(a, b);
+		e = frompow2(a, b, 4);
 		break;
 	case 32:
-		e = from32(a, b);
+		e = fromdecx(a, b, tab.t32, dec32);
 		break;
 	case 64:
-		e = from64(a, b);
+		e = fromdecx(a, b, tab.t64, dec64);
 		break;
+	default:
+		abort();
+		return nil;
 	}
 
+	if(pp != nil)
+		*pp = e;
+
 	// if no characters parsed, there wasn't a number to convert
 	if(e == a)
 		return nil;
 
-	if(pp != nil)
-		*pp = e;
-
 	b->sign = sign;
 	return mpnorm(b);
 }
--- /n/sources/plan9/sys/man/2/mp	Sat Jun 14 00:00:00 2025
+++ /sys/man/2/mp	Tue Jun 23 00:00:00 2026
@@ -343,7 +343,17 @@
 skips any leading spaces or tabs.
 .IR Strtomp 's
 scan stops when encountering a digit not valid in the
-base.  If
+base.
+If
+.I base
+is zero then C-style prefixes select the base:
+.B 0x
+for hexadecimal,
+.B 0b
+for binary and
+.B 0
+for octal. Otherwise decimal is assumed.
+If
 .I rptr
 is not zero,
 .I *rptr