diff --git a/server/app.ts b/server/app.ts
index e39905866..75c2e7224 100644
--- a/server/app.ts
+++ b/server/app.ts
@@ -763,12 +763,13 @@ export class Application implements ServerApplication {
   /** build the application to a static site(SSG) */
   async build() {
     const start = performance.now()
-    const outputDir = this.outputDir
-    const distDir = join(outputDir, '_aleph')
 
     // wait for app ready
     await this.ready
 
+    const outputDir = this.outputDir
+    const distDir = join(outputDir, '_aleph')
+
     // clear previous build
     if (existsDirSync(outputDir)) {
       for await (const entry of Deno.readDir(outputDir)) {