diff --git a/src/index.js b/src/index.js
index 1fce613..7fac33e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -18,7 +18,7 @@ import { BaseBlockstore } from 'blockstore-core/base'
 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')
   }