1 files changed, 13 insertions, 4 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 5b48f84a1..33abe9366 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -1467,16 +1467,25 @@ static BcStatus bc_num_ulong(BcNum *n, unsigned long *result_p)
 
 static void bc_num_ulong2num(BcNum *n, unsigned long val)
 {
-        size_t len;
         BcDig *ptr;
-        unsigned long i;
 
         bc_num_zero(n);
 
         if (val == 0) return;
 
-        for (len = 1, i = ULONG_MAX; i != 0; i /= 10, ++len) bc_num_expand(n, len);
-        for (ptr = n->num, i = 0; val; ++i, ++n->len, val /= 10) ptr[i] = val % 10;
+        if (ULONG_MAX == 0xffffffffUL)
+                bc_num_expand(n, 10); // 10 digits: 4294967295
+        if (ULONG_MAX == 0xffffffffffffffffUL)
+                bc_num_expand(n, 20); // 20 digits: 18446744073709551615
+        BUILD_BUG_ON(ULONG_MAX > 0xffffffffffffffffUL);
+
+        ptr = n->num;
+        for (;;) {
+                n->len++;
+                *ptr++ = val % 10;
+                val /= 10;
+                if (val == 0) break;
+        }
 }
 
 static void bc_num_subArrays(BcDig *restrict a, BcDig *restrict b,