diff --git a/src/setupWorker/setupWorker.ts b/src/setupWorker/setupWorker.ts
index 010047b0d..bce536114 100644
--- a/src/setupWorker/setupWorker.ts
+++ b/src/setupWorker/setupWorker.ts
@@ -19,6 +19,7 @@ import { createFallbackStop } from './stop/createFallbackStop'
 import { devUtils } from '../utils/internal/devUtils'
 import { SetupApi } from '../SetupApi'
 import { mergeRight } from '../utils/internal/mergeRight'
+import { SetupWorkerApi as ISetupWorkerApi } from './glossary'
 
 interface Listener {
   target: EventTarget
@@ -26,7 +27,7 @@ interface Listener {
   callback: EventListener
 }
 
-export class SetupWorkerApi extends SetupApi<WorkerLifecycleEventsMap> {
+class SetupWorkerApi extends SetupApi<WorkerLifecycleEventsMap> {
   private context: SetupWorkerInternalContext
   private startHandler: StartHandler = null as any
   private stopHandler: StopHandler = null as any
@@ -223,6 +224,6 @@ export class SetupWorkerApi extends SetupApi<WorkerLifecycleEventsMap> {
  */
 export function setupWorker(
   ...handlers: Array<RequestHandler>
-): SetupWorkerApi {
+): ISetupWorkerApi {
   return new SetupWorkerApi(...handlers)
 }