1 files changed, 8 insertions, 2 deletions
diff --git a/bignum.c b/bignum.c
index 7bcc4c7935..91c275e605 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1257,8 +1257,14 @@ rb_big2ull(VALUE x)
 {
     unsigned LONG_LONG num = big2ull(x, "unsigned long long");
 
-    if (!RBIGNUM_SIGN(x))
-	return (VALUE)(-(SIGNED_VALUE)num);
+    if (!RBIGNUM_SIGN(x)) {
+	VALUE v = (VALUE)(-(SIGNED_VALUE)num);
+
+	/* FIXNUM_MIN-1 .. LLONG_MIN mapped into 0xbfffffffffffffff .. LONG_MAX+1 */
+	if (v <= LLONG_MAX)
+	    rb_raise(rb_eRangeError, "bignum out of range of unsigned long long");
+	return v;
+    }
     return num;
 }