1 files changed, 3 insertions, 1 deletions
diff --git a/string.c b/string.c
index 487a863912..a9e90f2848 100644
--- a/string.c
+++ b/string.c
@@ -564,7 +564,9 @@ static VALUE rb_str_replace(VALUE, VALUE);
 VALUE
 rb_str_dup(VALUE str)
 {
-    return rb_str_new3(str);
+    VALUE dup = str_alloc(rb_obj_class(str));
+    rb_str_replace(dup, str);
+    return dup;
 }