diff --git a/src/sync/Mutex.ts b/src/sync/Mutex.ts
index 554c195..67e3b1c 100644
--- a/src/sync/Mutex.ts
+++ b/src/sync/Mutex.ts
@@ -1,6 +1,6 @@
-import { Token } from "../workers";
-import { mutexIdentityData } from "./identifiers";
-import { acquire, acquireAsync, SemaphoreInternal, type Releaser } from "./Semaphore";
+import type { Token } from "../workers.d.ts";
+import { mutexIdentityData } from "./identifiers.js";
+import { acquire, acquireAsync, SemaphoreInternal, type Releaser } from "./Semaphore.js";
 
 /**
  * Synchronization object that can be used to grant a single thread exclusive access to a resource or critical section.
diff --git a/src/sync/SyncObject.ts b/src/sync/SyncObject.ts
index acafe52..6b79b9c 100644
--- a/src/sync/SyncObject.ts
+++ b/src/sync/SyncObject.ts
@@ -1,4 +1,4 @@
-import { Token } from "../workers";
+import type { Token } from "../workers.d.ts";
 
 /**
  * Base class for synchronization objects.
diff --git a/src/sync/identifiers.ts b/src/sync/identifiers.ts
index c2891b7..a3a1d97 100644
--- a/src/sync/identifiers.ts
+++ b/src/sync/identifiers.ts
@@ -1,4 +1,4 @@
-import { type Token } from "../workers";
+import type { Token } from "../workers.d.ts";
 
 export type IdentifierData = [
     number,
diff --git a/src/workers/WorkItem.ts b/src/workers/WorkItem.ts
index 775a1d1..1a0f943 100644
--- a/src/workers/WorkItem.ts
+++ b/src/workers/WorkItem.ts
@@ -1,6 +1,6 @@
-import { CancelledMessage } from "../cancellation/CancelledMessage";
-import { WorkItemStatus } from "./AsyncWorker";
-import { WorkItemInternal } from "./WorkItemInternal";
+import { CancelledMessage } from "../cancellation/CancelledMessage.js";
+import { WorkItemStatus } from "./AsyncWorker.js";
+import { WorkItemInternal } from "./WorkItemInternal.js";
 
 /**
  * Defines a work item object, which is the abstract representation of a worker's task.