1 files changed, 1 insertions, 1 deletions
diff --git a/string.c b/string.c
index 8210f8dcb..4969b7513 100644
--- a/string.c
+++ b/string.c
@@ -117,7 +117,7 @@ rb_enc_str_coderange(VALUE str)
 	    while (p < e) {
 		int c = (unsigned char)*p;
 
-		if (c > 0x80) {
+		if (!isascii(c)) {
 		    cr = ENC_CODERANGE_MULTI;
 		    break;
 		}