1 files changed, 1 insertions, 1 deletions
diff --git a/bignum.c b/bignum.c
index b43b5993ba..88bf9e03e6 100644
--- a/bignum.c
+++ b/bignum.c
@@ -416,7 +416,7 @@ rb_cstr_to_inum(str, base, badcheck)
 	len = 2;
 	break;
       case 8:
-	if (str[0] == '0' && (str[1] == 'o'||str[1] == 'O')) {
+	if (str[0] == '0' && (str[1] == 'o'||str[1] == 'O'||str[1] == '_')) {
 	    str += 2;
 	}
       case 4: case 5: case 6: case 7: