diff --git a/build.sbt b/build.sbt
index 3a2908b3..2f2ccd57 100644
--- a/build.sbt
+++ b/build.sbt
@@ -28,9 +28,7 @@ run in Android := (run in (mobile, Android)).evaluated
 lazy val plugin = project
   .settings(commonSettings)
   .settings(
-    libraryDependencies ++=
-      "com.android.support" % "preference-v14" % supportLibsVersion ::
-      Nil
+    libraryDependencies += "com.android.support" % "preference-v14" % supportLibsVersion
   )
 
 lazy val mobile = project
diff --git a/mobile/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala b/mobile/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
index 82019164..d8d37808 100644
--- a/mobile/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
+++ b/mobile/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
@@ -161,8 +161,7 @@ class ShadowsocksVpnService extends VpnService with BaseService {
     }
   }
 
-  override protected def buildPluginCommandLine(): ArrayBuffer[String] =
-    super.buildPluginCommandLine() ++= Seq("-V")
+  override protected def buildPluginCommandLine(): ArrayBuffer[String] = super.buildPluginCommandLine() += "-V"
 
   def startShadowsocksDaemon() {
     val cmd = ArrayBuffer[String](getApplicationInfo.nativeLibraryDir + "/libss-local.so",