diff --git a/src/coincident.worker.ts b/src/coincident.worker.ts
index 9b25e97..245ceb5 100644
--- a/src/coincident.worker.ts
+++ b/src/coincident.worker.ts
@@ -72,9 +72,9 @@ export class XeusCoincidentKernel extends XeusRemoteKernel {
 
 const worker = new XeusCoincidentKernel();
 
-const sendWorkerMessage = workerAPI.processWorkerMessage.bind(workerAPI);
-worker.registerCallback(sendWorkerMessage);
-
 workerAPI.initialize = worker.initialize.bind(worker);
+workerAPI.mount = worker.mount.bind(worker);
+workerAPI.ready = worker.ready.bind(worker);
 workerAPI.cd = worker.cd.bind(worker);
 workerAPI.isDir = worker.isDir.bind(worker);
+workerAPI.processMessage = worker.processMessage.bind(worker);
diff --git a/src/web_worker_kernel.ts b/src/web_worker_kernel.ts
index 480cd37..befb0d5 100644
--- a/src/web_worker_kernel.ts
+++ b/src/web_worker_kernel.ts
@@ -70,9 +70,9 @@ export class WebWorkerKernel implements IKernel {
   ): IXeusWorkerKernel | Remote<IXeusWorkerKernel> {
     let remote: IXeusWorkerKernel | Remote<IXeusWorkerKernel>;
     if (crossOriginIsolated) {
+      this._worker.onmessage = this._processCoincidentWorkerMessage.bind(this);
+
       remote = coincident(this._worker) as IXeusWorkerKernel;
-      remote.processWorkerMessage =
-        this._processCoincidentWorkerMessage.bind(this);
       // The coincident worker uses its own filesystem API:
       (remote.processDriveRequest as any) = async <T extends TDriveMethod>(
         data: TDriveRequest<T>