diff --git a/src/utils/file.ts b/src/utils/file.ts
index 6ca0cb3..262367a 100644
--- a/src/utils/file.ts
+++ b/src/utils/file.ts
@@ -1,7 +1,7 @@
 import mime from "mime/lite";
 import path from "path";
 
-import { trimPrefix } from "./string.ts";
+import { trimPrefix } from "./string.js";
 
 /**
  * Get the file mime type. In case the type is not provided, try to guess the
diff --git a/src/utils/options.ts b/src/utils/options.ts
index edfec5f..3c8c613 100644
--- a/src/utils/options.ts
+++ b/src/utils/options.ts
@@ -1,4 +1,4 @@
-import { CustomClientOptions } from "../client.ts";
+import { CustomClientOptions } from "../client.js";
 
 // TODO: Unnecessary, remove.
 /**
diff --git a/src/utils/url.ts b/src/utils/url.ts
index a8166bd..8799b32 100644
--- a/src/utils/url.ts
+++ b/src/utils/url.ts
@@ -1,8 +1,8 @@
 import urljoin from "url-join";
 import parse from "url-parse";
 
-import { trimSuffix } from "./string.ts";
-import { throwValidationError } from "./validation.ts";
+import { trimSuffix } from "./string.js";
+import { throwValidationError } from "./validation.js";
 
 export const DEFAULT_S5_PORTAL_URL = "https://localhost:5522";