1 files changed, 9 insertions, 2 deletions
diff --git a/shell/math.c b/shell/math.c
index eaf4f2453..0c806ad39 100644
--- a/shell/math.c
+++ b/shell/math.c
@@ -538,9 +538,16 @@ static arith_t strto_arith_t(const char *nptr, char **endptr)
        n = 0;
        nptr = *endptr + 1;
        /* bash allows "N#" (empty "nnnn" part) */
-        while (isdigit(*nptr)) {
+        for (;;) {
+                unsigned digit = (unsigned)*nptr - '0';
+                if (digit >= 10 || digit >= base) {
+                        digit = (unsigned)(*nptr | 0x20) - ('a' - 10);
+                        if (digit >= base)
+                                break;
+                }
                /* bash does not check for overflows */
-                n = n * base + (*nptr++ - '0');
+                n = n * base + digit;
+                nptr++;
        }
        *endptr = (char*)nptr;
        return n;