diff --git a/build.sbt b/build.sbt
index 51701dae..a0eeb512 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,15 +1,17 @@
 import android.Keys._
 
-import android.Dependencies.{apklib,aar}
-
 android.Plugin.androidBuild
 
-platformTarget in Android := "android-21"
+platformTarget in Android := "android-22"
 
 name := "shadowsocks"
 
 compileOrder in Compile := CompileOrder.JavaThenScala
 
+javacOptions ++= Seq("-source", "1.6", "-target", "1.6")
+
+scalacOptions += "-target:jvm-1.6"
+
 ndkJavah in Android := List()
 
 ndkBuild in Android := List()
diff --git a/src/main/AndroidManifest.xml b/src/main/AndroidManifest.xml
index 2c5312f2..30704809 100644
--- a/src/main/AndroidManifest.xml
+++ b/src/main/AndroidManifest.xml
@@ -14,7 +14,7 @@
 
   <uses-sdk
       android:minSdkVersion="16"
-      android:targetSdkVersion="21"/>
+      android:targetSdkVersion="22"/>
 
   <application
       android:allowBackup="true"
diff --git a/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala b/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala
index d950f395..adce3e27 100644
--- a/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala
+++ b/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala
@@ -41,6 +41,7 @@ package com.github.shadowsocks
 
 import java.io.File
 import java.lang.reflect.{InvocationTargetException, Method}
+import java.net.{Inet6Address, InetAddress}
 import java.util.Locale
 
 import android.app._
@@ -54,7 +55,6 @@ import android.widget.Toast
 import com.github.shadowsocks.aidl.Config
 import com.github.shadowsocks.utils._
 import com.google.android.gms.analytics.HitBuilders
-import org.apache.http.conn.util.InetAddressUtils
 
 import scala.collection._
 import scala.collection.mutable.ArrayBuffer
@@ -430,7 +430,7 @@ class ShadowsocksNatService extends Service with BaseService {
     init_sb.append(Utils.getIptables + " -t nat -F OUTPUT")
 
     val cmd_bypass = Utils.getIptables + CMD_IPTABLES_RETURN
-    if (!InetAddressUtils.isIPv6Address(config.proxy.toUpperCase)) {
+    if (!InetAddress.getByName(config.proxy.toUpperCase).isInstanceOf[Inet6Address]) {
       init_sb.append(cmd_bypass.replace("-p tcp -d 0.0.0.0", "-d " + config.proxy))
     }
     init_sb.append(cmd_bypass.replace("-p tcp -d 0.0.0.0", "-d 127.0.0.1"))
@@ -576,8 +576,7 @@ class ShadowsocksNatService extends Service with BaseService {
         killProcesses()
 
         var resolved: Boolean = false
-        if (!InetAddressUtils.isIPv4Address(config.proxy) &&
-          !InetAddressUtils.isIPv6Address(config.proxy)) {
+        if (!Utils.isNumeric(config.proxy)) {
           Utils.resolve(config.proxy, enableIPv6 = true) match {
             case Some(a) =>
               config.proxy = a
diff --git a/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala b/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
index 2714ae35..19bb4b7c 100644
--- a/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
+++ b/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
@@ -40,6 +40,7 @@
 package com.github.shadowsocks
 
 import java.io.File
+import java.net.InetAddress
 import java.util.Locale
 
 import android.app._
@@ -53,7 +54,6 @@ import com.github.shadowsocks.aidl.Config
 import com.github.shadowsocks.utils._
 import com.google.android.gms.analytics.HitBuilders
 import org.apache.commons.net.util.SubnetUtils
-import org.apache.http.conn.util.InetAddressUtils
 
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
@@ -238,8 +238,7 @@ class ShadowsocksVpnService extends VpnService with BaseService {
 
         // Resolve the server address
         var resolved: Boolean = false
-        if (!InetAddressUtils.isIPv4Address(config.proxy) &&
-          !InetAddressUtils.isIPv6Address(config.proxy)) {
+        if (!Utils.isNumeric(config.proxy)) {
           Utils.resolve(config.proxy, enableIPv6 = true) match {
             case Some(addr) =>
               config.proxy = addr
diff --git a/src/main/scala/com/github/shadowsocks/utils/Utils.scala b/src/main/scala/com/github/shadowsocks/utils/Utils.scala
index 6ce7183d..9581a74c 100644
--- a/src/main/scala/com/github/shadowsocks/utils/Utils.scala
+++ b/src/main/scala/com/github/shadowsocks/utils/Utils.scala
@@ -44,8 +44,7 @@ import android.content.pm.PackageManager
 import android.graphics.drawable.{BitmapDrawable, Drawable}
 import android.util.{Base64, Log}
 import java.io._
-import java.net.{UnknownHostException, InetAddress, NetworkInterface}
-import org.apache.http.conn.util.InetAddressUtils
+import java.net._
 import org.xbill.DNS._
 import android.graphics._
 import android.app.ActivityManager
@@ -233,6 +232,9 @@ object Utils {
     None
   }
 
+  lazy val isNumericMethod = classOf[InetAddress].getMethod("isNumeric", classOf[String])
+  def isNumeric(address: String): Boolean = isNumericMethod.invoke(null, address).asInstanceOf[Boolean]
+
   /**
    * Get local IPv4 address
    */
@@ -245,9 +247,8 @@ object Utils {
         while (addrs.hasMoreElements) {
           val addr = addrs.nextElement()
           if (!addr.isLoopbackAddress && !addr.isLinkLocalAddress) {
-            val sAddr = addr.getHostAddress.toUpperCase
-            if (InetAddressUtils.isIPv4Address(sAddr)) {
-              return Some(sAddr)
+            if (addr.isInstanceOf[Inet4Address]) {
+              return Some(addr.getHostAddress.toUpperCase)
             }
           }
         }
@@ -271,8 +272,7 @@ object Utils {
         while (addrs.hasMoreElements) {
           val addr = addrs.nextElement()
           if (!addr.isLoopbackAddress && !addr.isLinkLocalAddress) {
-            val sAddr = addr.getHostAddress.toUpperCase
-            if (InetAddressUtils.isIPv6Address(sAddr)) {
+            if (addr.isInstanceOf[Inet6Address]) {
               if (BuildConfig.DEBUG) Log.d(TAG, "IPv6 address detected")
               return true
             }