diff --git a/lib/index.js b/lib/index.js
index d068406..2b516ca 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -353,7 +353,7 @@ Channel.from = (values, mapfn, thisArg) => {
 };
 
 Channel.of = (...values) => Channel.from(values);
-Channel.isChannel = arg => prototype.isPrototypeOf(arg);
+Channel.isChannel = arg => Object.getPrototypeOf(arg) === prototype;
 
 Channel.select = methodPromises =>
   Object.assign(