diff --git a/core/build.gradle b/core/build.gradle
index ed65a0e7af..6f84de0186 100644
--- a/core/build.gradle
+++ b/core/build.gradle
@@ -67,7 +67,6 @@ dependencies {
     api 'com.crashlytics.sdk.android:crashlytics:2.9.8'
     api 'com.google.firebase:firebase-config:16.1.3'
     api 'com.google.firebase:firebase-core:16.0.6'
-    api 'com.squareup.okhttp3:okhttp:3.12.1'
     api "com.takisoft.preferencex:preferencex:$preferencexVersion"
     api 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.1.0'
     kapt "androidx.lifecycle:lifecycle-compiler:$lifecycleVersion"
diff --git a/core/src/main/java/com/github/shadowsocks/bg/ProxyInstance.kt b/core/src/main/java/com/github/shadowsocks/bg/ProxyInstance.kt
index 7b554d79d5..790844cdec 100644
--- a/core/src/main/java/com/github/shadowsocks/bg/ProxyInstance.kt
+++ b/core/src/main/java/com/github/shadowsocks/bg/ProxyInstance.kt
@@ -36,11 +36,9 @@ import com.github.shadowsocks.utils.signaturesCompat
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import kotlinx.coroutines.withTimeout
-import okhttp3.FormBody
-import okhttp3.OkHttpClient
-import okhttp3.Request
 import java.io.File
 import java.io.IOException
+import java.net.HttpURLConnection
 import java.net.InetAddress
 import java.net.UnknownHostException
 import java.security.MessageDigest
@@ -56,19 +54,23 @@ class ProxyInstance(val profile: Profile, private val route: String = profile.ro
 
     suspend fun init() {
         if (profile.host == "198.199.101.152") {
-            val client = OkHttpClient.Builder().build()
             val mdg = MessageDigest.getInstance("SHA-1")
             mdg.update(Core.packageInfo.signaturesCompat.first().toByteArray())
-            val requestBody = FormBody.Builder()
-                    .add("sig", String(Base64.encode(mdg.digest(), 0)))
-                    .build()
-            val request = Request.Builder()
-                    .url(RemoteConfig.proxyUrl)
-                    .post(requestBody)
-                    .build()
-
-            val proxies = withTimeout(30_000) {
-                withContext(Dispatchers.IO) { client.newCall(request).execute().body()!!.string() }
+            val conn = RemoteConfig.proxyUrl.openConnection() as HttpURLConnection
+            conn.requestMethod = "POST"
+            conn.doOutput = true
+
+            val proxies = try {
+                withTimeout(30_000) {
+                    withContext(Dispatchers.IO) {
+                        conn.outputStream.bufferedWriter().use {
+                            it.write("sig=" + String(Base64.encode(mdg.digest(), Base64.DEFAULT)))
+                        }
+                        conn.inputStream.bufferedReader().readText()
+                    }
+                }
+            } finally {
+                conn.disconnect()
             }.split('|').toMutableList()
             proxies.shuffle()
             val proxy = proxies.first().split(':')
diff --git a/core/src/main/java/com/github/shadowsocks/bg/RemoteConfig.kt b/core/src/main/java/com/github/shadowsocks/bg/RemoteConfig.kt
index 41f9dedacc..52ee8536a8 100644
--- a/core/src/main/java/com/github/shadowsocks/bg/RemoteConfig.kt
+++ b/core/src/main/java/com/github/shadowsocks/bg/RemoteConfig.kt
@@ -25,11 +25,12 @@ import androidx.core.os.bundleOf
 import com.github.shadowsocks.Core
 import com.github.shadowsocks.core.R
 import com.google.firebase.remoteconfig.FirebaseRemoteConfig
+import java.net.URL
 
 object RemoteConfig {
     private val config = FirebaseRemoteConfig.getInstance().apply { setDefaults(R.xml.default_configs) }
 
-    val proxyUrl get() = config.getString("proxy_url")
+    val proxyUrl get() = URL(config.getString("proxy_url"))
 
     fun fetch() = config.fetch().addOnCompleteListener {
         if (it.isSuccessful) config.activateFetched() else {
diff --git a/mobile/proguard-rules.pro b/mobile/proguard-rules.pro
index 2cb20319a2..12896c28c4 100644
--- a/mobile/proguard-rules.pro
+++ b/mobile/proguard-rules.pro
@@ -22,5 +22,3 @@
 #-renamesourcefileattribute SourceFile
 
 -dontwarn com.google.android.gms.internal.**
--dontwarn okhttp3.**
--dontwarn okio.**
diff --git a/tv/proguard-rules.pro b/tv/proguard-rules.pro
index 2cb20319a2..12896c28c4 100644
--- a/tv/proguard-rules.pro
+++ b/tv/proguard-rules.pro
@@ -22,5 +22,3 @@
 #-renamesourcefileattribute SourceFile
 
 -dontwarn com.google.android.gms.internal.**
--dontwarn okhttp3.**
--dontwarn okio.**