diff --git a/src/lib/preflight.ts b/src/lib/preflight.ts
index c59723f8c63..8f874e3b6c1 100644
--- a/src/lib/preflight.ts
+++ b/src/lib/preflight.ts
@@ -137,7 +137,7 @@ export async function checkPortAvailable(
   port?: number,
   opts?: CheckPortOpts,
 ): Promise<PortProbeResult> {
-  const p = port || 18789;
+  const p = port ?? 18789;
   const o = opts || {};
 
   // ── lsof path ──────────────────────────────────────────────────