diff --git a/packages/core/clockworker.js b/packages/core/clockworker.js
index e2f6b25d..89f0f9f1 100644
--- a/packages/core/clockworker.js
+++ b/packages/core/clockworker.js
@@ -79,7 +79,7 @@ const processMessage = (message) => {
   }
 };
 
-onconnect = function (e) {
+this.onconnect = function (e) {
   // the incoming port
   const port = e.ports[0];
   allPorts.push(port);