diff --git a/vite.config.ts b/vite.config.ts
index 404d07e..f5688dd 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -1,20 +1,22 @@
 import path from "path";
-import { ServerOptions as HttpsServerOptions } from "https";
+import { ServerOptions } from "https";
 import { defineConfig, loadEnv } from "vite";
 import vue from "@vitejs/plugin-vue";
 import ViteYaml from "@modyfi/vite-plugin-yaml";
 import { visualizer } from "rollup-plugin-visualizer";
 
+type HttpsOptions = Pick<ServerOptions, "key" | "cert">;
+
 // https://vitejs.dev/config/
 export default defineConfig(async ({ mode }) => {
   // Load .env files. Vite will do it itself, but only later. See https://github.com/vitejs/vite/issues/1930
   Object.assign(process.env, loadEnv(mode, process.cwd(), ""));
 
-  // Read HTTPS cert and key, if their paths are specified in env.
-  async function getHttpsOptions(): Promise<HttpsServerOptions | undefined> {
+  /** Read HTTPS cert and key, if their paths are specified in env. */
+  async function getHttpsOptions(): Promise<HttpsOptions | undefined> {
     if (process.env.DEV_HTTPS_KEY && process.env.DEV_HTTPS_CERT) {
       const fs = await import("fs");
-      return <HttpsServerOptions>{
+      return {
         key: fs.readFileSync(process.env.DEV_HTTPS_KEY),
         cert: fs.readFileSync(process.env.DEV_HTTPS_CERT),
       };