diff --git a/app/src/main/java/io/nekohasekai/sagernet/Constants.kt b/app/src/main/java/io/nekohasekai/sagernet/Constants.kt
index 8b64284..4d29104 100644
--- a/app/src/main/java/io/nekohasekai/sagernet/Constants.kt
+++ b/app/src/main/java/io/nekohasekai/sagernet/Constants.kt
@@ -90,6 +90,7 @@ object Key {
     const val SERVER_ENCRYPTION = "serverEncryption"
     const val SERVER_ALPN = "serverALPN"
     const val SERVER_CERTIFICATES = "serverCertificates"
+    const val SERVER_MTU = "serverMTU"
 
     const val SERVER_CONFIG = "serverConfig"
     const val SERVER_CUSTOM = "serverCustom"
diff --git a/app/src/main/java/io/nekohasekai/sagernet/bg/proto/BoxInstance.kt b/app/src/main/java/io/nekohasekai/sagernet/bg/proto/BoxInstance.kt
index 0f20337..bca90d0 100644
--- a/app/src/main/java/io/nekohasekai/sagernet/bg/proto/BoxInstance.kt
+++ b/app/src/main/java/io/nekohasekai/sagernet/bg/proto/BoxInstance.kt
@@ -147,6 +147,7 @@ abstract class BoxInstance(
 
                         val envMap = mutableMapOf<String, String>()
                         envMap["MIERU_CONFIG_JSON_FILE"] = configFile.absolutePath
+                        envMap["MIERU_PROTECT_PATH"] = "protect_path"
 
                         val commands = mutableListOf(
                             initPlugin("mieru-plugin").path, "run",
diff --git a/app/src/main/java/io/nekohasekai/sagernet/database/DataStore.kt b/app/src/main/java/io/nekohasekai/sagernet/database/DataStore.kt
index e868b9b..20cf811 100644
--- a/app/src/main/java/io/nekohasekai/sagernet/database/DataStore.kt
+++ b/app/src/main/java/io/nekohasekai/sagernet/database/DataStore.kt
@@ -189,6 +189,7 @@ object DataStore : OnPreferenceDataStoreChangeListener {
     var serverEncryption by profileCacheStore.string(Key.SERVER_ENCRYPTION)
     var serverALPN by profileCacheStore.string(Key.SERVER_ALPN)
     var serverCertificates by profileCacheStore.string(Key.SERVER_CERTIFICATES)
+    var serverMTU by profileCacheStore.stringToInt(Key.SERVER_MTU)
     var serverHeaders by profileCacheStore.string(Key.SERVER_HEADERS)
     var serverAllowInsecure by profileCacheStore.boolean(Key.SERVER_ALLOW_INSECURE)
 
diff --git a/app/src/main/java/io/nekohasekai/sagernet/fmt/mieru/MieruFmt.kt b/app/src/main/java/io/nekohasekai/sagernet/fmt/mieru/MieruFmt.kt
index 4085216..476999a 100644
--- a/app/src/main/java/io/nekohasekai/sagernet/fmt/mieru/MieruFmt.kt
+++ b/app/src/main/java/io/nekohasekai/sagernet/fmt/mieru/MieruFmt.kt
@@ -47,6 +47,7 @@ fun MieruBean.buildMieruConfig(port: Int): String {
                     put("password", password)
                 })
                 put("servers", serverInfo)
+                put("mtu", mtu)
             })
         })
     }.toStringPretty()
diff --git a/app/src/main/java/io/nekohasekai/sagernet/ui/profile/MieruSettingsActivity.kt b/app/src/main/java/io/nekohasekai/sagernet/ui/profile/MieruSettingsActivity.kt
index f9195fb..41c12cf 100644
--- a/app/src/main/java/io/nekohasekai/sagernet/ui/profile/MieruSettingsActivity.kt
+++ b/app/src/main/java/io/nekohasekai/sagernet/ui/profile/MieruSettingsActivity.kt
@@ -41,7 +41,7 @@ class MieruSettingsActivity : ProfileSettingsActivity<MieruBean>() {
         DataStore.serverProtocol = protocol
         DataStore.serverUsername = username
         DataStore.serverPassword = password
-        DataStore.mtu = mtu
+        DataStore.serverMTU = mtu
     }
 
     override fun MieruBean.serialize() {
@@ -51,7 +51,7 @@ class MieruSettingsActivity : ProfileSettingsActivity<MieruBean>() {
         protocol = DataStore.serverProtocol
         username = DataStore.serverUsername
         password = DataStore.serverPassword
-        mtu = DataStore.mtu
+        mtu = DataStore.serverMTU
     }
 
     override fun PreferenceFragmentCompat.createPreferences(
@@ -66,7 +66,7 @@ class MieruSettingsActivity : ProfileSettingsActivity<MieruBean>() {
             summaryProvider = PasswordSummaryProvider
         }
         val protocol = findPreference<SimpleMenuPreference>(Key.SERVER_PROTOCOL)!!
-        val mtu = findPreference<EditTextPreference>(Key.MTU)!!
+        val mtu = findPreference<EditTextPreference>(Key.SERVER_MTU)!!
         mtu.isVisible = protocol.value.equals("UDP")
         protocol.setOnPreferenceChangeListener { _, newValue ->
             mtu.isVisible = newValue.equals("UDP")
diff --git a/app/src/main/res/xml/mieru_preferences.xml b/app/src/main/res/xml/mieru_preferences.xml
index 19a3dab..aecc8f0 100644
--- a/app/src/main/res/xml/mieru_preferences.xml
+++ b/app/src/main/res/xml/mieru_preferences.xml
@@ -38,7 +38,7 @@
             app:title="@string/password" />
         <EditTextPreference
             app:icon="@drawable/baseline_public_24"
-            app:key="mtu"
+            app:key="serverMTU"
             app:title="@string/mtu"
             app:useSimpleSummaryProvider="true" />
     </PreferenceCategory>