diff --git a/README.md b/README.md
index 41aa094..3804742 100644
--- a/README.md
+++ b/README.md
@@ -4,3 +4,6 @@
 - Store: https://kunkun.sh/store/disk-speed
 
 ![](https://i.imgur.com/8ISVrRe.png)
+
+This extension's read speed is not accurate. Your OS may cache the test data and result in a much higher speed.
+Will be fixed in the future.
diff --git a/package.json b/package.json
index 9159c36..dfa60d7 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
   "name": "kunkun-ext-disk-speed",
   "license": "MIT",
   "repository": "https://github.com/kunkunsh/kunkun-ext-disk-speed",
-  "version": "0.0.7",
+  "version": "0.0.8",
   "type": "module",
   "kunkun": {
     "name": "Disk Speed",
diff --git a/src/App.svelte b/src/App.svelte
index 7b5f0be..0255841 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -126,6 +126,10 @@
     <Button disabled={!$targetDir || running} on:click={startSpeedTest}>
       Start Speed Test
     </Button>
+    <small class="text-gray-500">
+      This extension's read speed may be inaccurate. Your OS may cache the test
+      data and result in a much higher speed. Will be fixed in the future.
+    </small>
     <div class="grid h-96 w-full grid-cols-2">
       <SpeedGauge
         speedInMBps={writeSpeedMBps}
diff --git a/src/lib/store.ts b/src/lib/store.ts
index 4789c4a..0c0acf9 100644
--- a/src/lib/store.ts
+++ b/src/lib/store.ts
@@ -1,4 +1,4 @@
 import { writable } from "svelte/store";
 
 export const stress = writable(1);
-export const targetDir = writable<string | undefined>("/Volumes/Portable2TB");
+export const targetDir = writable<string | undefined>(undefined);