diff --git a/cid.js b/cid.js
index 1c350888..bc0d152f 100644
--- a/cid.js
+++ b/cid.js
@@ -29,6 +29,7 @@ export default multiformats => {
         writable: false,
         enumerable: false
       })
+      readonly(this, 'asCID', this)
       if (_CID.isCID(cid)) {
         readonly(this, 'version', cid.version)
         readonly(this, 'multihash', bytes.coerce(cid.multihash))