diff --git a/src/index.js b/src/index.js
index e90fd80..0d86f67 100644
--- a/src/index.js
+++ b/src/index.js
@@ -20,7 +20,7 @@ const { BlockstoreAdapter } = require('interface-blockstore')
 function cidToKey (cid) {
   const c = CID.asCID(cid)
 
-  if (!(c instanceof CID)) {
+  if (!c) {
     throw errcode(new Error('Not a valid cid'), 'ERR_INVALID_CID')
   }