diff --git a/src/main/scala/gitbucket/core/plugin/PluginRegistory.scala b/src/main/scala/gitbucket/core/plugin/PluginRegistory.scala
index dfd659a..22264fe 100644
--- a/src/main/scala/gitbucket/core/plugin/PluginRegistory.scala
+++ b/src/main/scala/gitbucket/core/plugin/PluginRegistory.scala
@@ -24,7 +24,6 @@
 
 import scala.collection.mutable
 import scala.collection.mutable.ListBuffer
-import com.github.zafarkhaja.semver.{Version => Semver}
 
 class PluginRegistry {
 
@@ -190,6 +189,7 @@
   private var instance = new PluginRegistry()
 
   private var watcher: PluginWatchThread = null
+  private var extraWatcher: PluginWatchThread = null
 
   /**
    * Returns the PluginRegistry singleton instance.
@@ -242,6 +242,8 @@
     }).toSeq.sortBy(_.getName).reverse
   }
 
+  lazy val extraPluginDir: Option[String] = Option(System.getProperty("gitbucket.pluginDir"))
+
   /**
    * Initializes all installed plugins.
    */
@@ -256,57 +258,65 @@
     }
     installedDir.mkdir()
 
-    if(pluginDir.exists && pluginDir.isDirectory) {
-      pluginDir.listFiles(new FilenameFilter {
-        override def accept(dir: File, name: String): Boolean = name.endsWith(".jar")
-      }).toSeq.sortBy(_.getName).reverse.foreach { pluginJar =>
+    val pluginJars = listPluginJars(pluginDir)
+    val extraJars = extraPluginDir.map { extraDir => listPluginJars(new File(extraDir)) }.getOrElse(Nil)
 
-        val installedJar = new File(installedDir, pluginJar.getName)
-        FileUtils.copyFile(pluginJar, installedJar)
+    (extraJars ++ pluginJars).foreach { pluginJar =>
+      val installedJar = new File(installedDir, pluginJar.getName)
+      FileUtils.copyFile(pluginJar, installedJar)
 
-        logger.info(s"Initialize ${pluginJar.getName}")
-        val classLoader = new URLClassLoader(Array(installedJar.toURI.toURL), Thread.currentThread.getContextClassLoader)
-        try {
-          val plugin = classLoader.loadClass("Plugin").getDeclaredConstructor().newInstance().asInstanceOf[Plugin]
-          val pluginId = plugin.pluginId
-          // Check duplication
-          instance.getPlugins().find(_.pluginId == pluginId).foreach { x =>
-            throw new IllegalStateException(s"Plugin ${pluginId} is duplicated. ${x.pluginJar.getName} is available.")
+      logger.info(s"Initialize ${pluginJar.getName}")
+      val classLoader = new URLClassLoader(Array(installedJar.toURI.toURL), Thread.currentThread.getContextClassLoader)
+      try {
+        val plugin = classLoader.loadClass("Plugin").getDeclaredConstructor().newInstance().asInstanceOf[Plugin]
+        val pluginId = plugin.pluginId
+
+        // Check duplication
+        instance.getPlugins().find(_.pluginId == pluginId) match {
+          case Some(x) => {
+            logger.warn(s"Plugin ${pluginId} is duplicated. ${x.pluginJar.getName} is available.")
           }
+          case None => {
+            // Migration
+            val solidbase = new Solidbase()
+            solidbase.migrate(conn, classLoader, DatabaseConfig.liquiDriver, new Module(plugin.pluginId, plugin.versions: _*))
 
-          // Migration
-          val solidbase = new Solidbase()
-          solidbase.migrate(conn, classLoader, DatabaseConfig.liquiDriver, new Module(plugin.pluginId, plugin.versions: _*))
+            // Check database version
+            val databaseVersion = manager.getCurrentVersion(plugin.pluginId)
+            val pluginVersion = plugin.versions.last.getVersion
+            if (databaseVersion != pluginVersion) {
+              throw new IllegalStateException(s"Plugin version is ${pluginVersion}, but database version is ${databaseVersion}")
+            }
 
-          // Check database version
-          val databaseVersion = manager.getCurrentVersion(plugin.pluginId)
-          val pluginVersion = plugin.versions.last.getVersion
-          if (databaseVersion != pluginVersion) {
-            throw new IllegalStateException(s"Plugin version is ${pluginVersion}, but database version is ${databaseVersion}")
+            // Initialize
+            plugin.initialize(instance, context, settings)
+            instance.addPlugin(PluginInfo(
+              pluginId      = plugin.pluginId,
+              pluginName    = plugin.pluginName,
+              pluginVersion = plugin.versions.last.getVersion,
+              description   = plugin.description,
+              pluginClass   = plugin,
+              pluginJar     = pluginJar,
+              classLoader   = classLoader
+            ))
           }
-
-          // Initialize
-          plugin.initialize(instance, context, settings)
-          instance.addPlugin(PluginInfo(
-            pluginId      = plugin.pluginId,
-            pluginName    = plugin.pluginName,
-            pluginVersion = plugin.versions.last.getVersion,
-            description   = plugin.description,
-            pluginClass   = plugin,
-            pluginJar     = pluginJar,
-            classLoader   = classLoader
-          ))
-
-        } catch {
-          case e: Throwable => logger.error(s"Error during plugin initialization: ${pluginJar.getName}", e)
         }
+      } catch {
+        case e: Throwable => logger.error(s"Error during plugin initialization: ${pluginJar.getName}", e)
       }
     }
 
     if(watcher == null){
-      watcher = new PluginWatchThread(context)
+      watcher = new PluginWatchThread(context, PluginHome)
       watcher.start()
     }
+
+    extraPluginDir.foreach { extraDir =>
+      if(extraWatcher == null){
+        extraWatcher = new PluginWatchThread(context, extraDir)
+        extraWatcher.start()
+      }
+    }
   }
 
   def shutdown(context: ServletContext, settings: SystemSettings): Unit = synchronized {
@@ -349,14 +359,14 @@
   classLoader: URLClassLoader
 ) extends PluginInfoBase(pluginId, pluginName, pluginVersion, description)
 
-class PluginWatchThread(context: ServletContext) extends Thread with SystemSettingsService {
+class PluginWatchThread(context: ServletContext, dir: String) extends Thread with SystemSettingsService {
   import gitbucket.core.model.Profile.profile.blockingApi._
   import scala.collection.JavaConverters._
 
   private val logger = LoggerFactory.getLogger(classOf[PluginWatchThread])
 
   override def run(): Unit = {
-    val path = Paths.get(PluginHome)
+    val path = Paths.get(dir)
     if(!Files.exists(path)){
       Files.createDirectories(path)
     }
@@ -374,7 +384,9 @@
     try {
       while (watchKey.isValid()) {
         val detectedWatchKey = watcher.take()
-        val events = detectedWatchKey.pollEvents.asScala.filter(_.context.toString != ".installed")
+        val events = detectedWatchKey.pollEvents.asScala.filter { e =>
+          e.context.toString != ".installed" && !e.context.toString.endsWith(".bak")
+        }
         if(events.nonEmpty){
           events.foreach { event =>
             logger.info(event.kind + ": " + event.context)
diff --git a/src/main/scala/gitbucket/core/util/Directory.scala b/src/main/scala/gitbucket/core/util/Directory.scala
index 73adcfd..e4d3b4a 100644
--- a/src/main/scala/gitbucket/core/util/Directory.scala
+++ b/src/main/scala/gitbucket/core/util/Directory.scala
@@ -32,7 +32,7 @@
 
   val DatabaseHome = s"${GitBucketHome}/data"
 
-  val PluginHome = Option(System.getProperty("gitbucket.pluginDir")).getOrElse(s"${GitBucketHome}/plugins")
+  val PluginHome = s"${GitBucketHome}/plugins"
 
   val TemporaryHome = s"${GitBucketHome}/tmp"