1 files changed, 4 insertions, 3 deletions
diff --git a/bignum.c b/bignum.c
index 6d1b5547a5..8fdcf72653 100644
--- a/bignum.c
+++ b/bignum.c
@@ -512,10 +512,11 @@ rb_cstr_to_inum(str, base, badcheck)
     for (i=len;i--;) zds[i]=0;
     while ((c = *str++) != 0) {
 	if (c == '_') {
-	    if (badcheck) {
-		if (nondigit) goto bad;
-		nondigit = c;
+	    if (nondigit) {
+		if (badcheck) goto bad;
+		break;
 	    }
+	    nondigit = c;
 	    continue;
 	}
 	else if ((c = conv_digit(c)) < 0) {