1 files changed, 2 insertions, 1 deletions
diff --git a/bignum.c b/bignum.c
index 8815a43808..fb469e1a84 100644
--- a/bignum.c
+++ b/bignum.c
@@ -104,7 +104,7 @@ bigtrunc(x)
     long len = RBIGNUM(x)->len;
     BDIGIT *ds = BDIGITS(x);
 
-    while (len-- && !ds[len]);
+    while (--len && !ds[len]);
     RBIGNUM(x)->len = ++len;
     return x;
 }
@@ -1100,6 +1100,7 @@ rb_big_neg(x)
     if (!RBIGNUM(x)->sign) get2comp(z);
     ds = BDIGITS(z);
     i = RBIGNUM(x)->len;
+    if (!i) return INT2FIX(~(SIGNED_VALUE)0);
     while (i--) ds[i] = ~ds[i];
     RBIGNUM(z)->sign = !RBIGNUM(z)->sign;
     if (RBIGNUM(x)->sign) get2comp(z);