diff --git a/build.sbt b/build.sbt
index 571561334..1849ca8df 100644
--- a/build.sbt
+++ b/build.sbt
@@ -3,7 +3,7 @@ import scala.util.Try
 name := "scorex-core"
 
 lazy val commonSettings = Seq(
-  scalaVersion := "2.12.3",
+  scalaVersion := "2.12.10",
   resolvers += Resolver.sonatypeRepo("public"),
   wartremoverErrors ++= Seq(
     Wart.Recursion,
@@ -96,7 +96,7 @@ val loggingDependencies = Seq(
   "ch.qos.logback" % "logback-classic" % "1.3.0-alpha4"
 )
 
-val scorexUtil = "org.scorexfoundation" %% "scorex-util" % "0.1.6"
+val scorexUtil = "org.scorexfoundation" %% "scorex-util" % "0.1.7"
 
 val testingDependencies = Seq(
   "com.typesafe.akka" %% "akka-testkit" % akkaVersion % "test",
diff --git a/src/main/scala/scorex/core/core.scala b/src/main/scala/scorex/core/core.scala
index 020c1ee0d..ff252ac1b 100644
--- a/src/main/scala/scorex/core/core.scala
+++ b/src/main/scala/scorex/core/core.scala
@@ -10,17 +10,9 @@ package object core {
   //TODO implement ModifierTypeId as a trait
   object ModifierTypeId extends TaggedType[Byte]
 
-  @deprecated("use `scorex.util.ModifierId`", "")
-  type ModifierId = scorex.util.ModifierId.Type
-
-  @deprecated("use `scorex.util.ModifierId`", "")
-  val ModifierId: scorex.util.ModifierId.type = scorex.util.ModifierId
-
-  object VersionTag extends TaggedType[String]
-
   type ModifierTypeId = ModifierTypeId.Type
 
-  type VersionTag = VersionTag.Type
+  type VersionTag = util.ModifierId
 
   def idsToString(ids: Seq[(ModifierTypeId, util.ModifierId)])(implicit enc: ScorexEncoder): String = {
     List(ids.headOption, ids.lastOption)
@@ -39,12 +31,12 @@ package object core {
 
   def idToBytes: util.ModifierId => Array[Byte] = scorex.util.idToBytes
 
-  def bytesToVersion(bytes: Array[Byte]): VersionTag = VersionTag @@ Base16.encode(bytes)
+  def bytesToVersion(bytes: Array[Byte]): VersionTag = scorex.util.bytesToId(bytes)
 
-  def versionToBytes(id: VersionTag): Array[Byte] = Base16.decode(id).get
+  def versionToBytes(id: VersionTag): Array[Byte] = scorex.util.idToBytes(id)
 
-  def versionToId(version: VersionTag): util.ModifierId = util.ModifierId @@ version
+  def versionToId(version: VersionTag): util.ModifierId = version
 
-  def idToVersion(id: util.ModifierId): VersionTag = VersionTag @@ id
+  def idToVersion(id: util.ModifierId): VersionTag = id
 
 }
diff --git a/src/main/scala/scorex/core/utils/ScorexEncoder.scala b/src/main/scala/scorex/core/utils/ScorexEncoder.scala
index 1e9bf2b68..071efd0f9 100644
--- a/src/main/scala/scorex/core/utils/ScorexEncoder.scala
+++ b/src/main/scala/scorex/core/utils/ScorexEncoder.scala
@@ -30,7 +30,7 @@ class ScorexEncoder extends BytesEncoder {
     * with encode() and decode methods
     */
   @inline
-  def encodeVersion(input: VersionTag): String = input
+  def encodeVersion(input: VersionTag): String = input.toString
 
   /**
     * This method might be useful and reimplemented, if encoding of ModifierId and VersionTag
@@ -38,7 +38,7 @@ class ScorexEncoder extends BytesEncoder {
     * with encode() and decode methods
     */
   @inline
-  def encodeId(input: ModifierId): String = input
+  def encodeId(input: ModifierId): String = input.toString
 
 }
 
diff --git a/testkit/src/main/scala/scorex/testkit/utils/FileUtils.scala b/testkit/src/main/scala/scorex/testkit/utils/FileUtils.scala
index 4417b68f0..b7492d304 100644
--- a/testkit/src/main/scala/scorex/testkit/utils/FileUtils.scala
+++ b/testkit/src/main/scala/scorex/testkit/utils/FileUtils.scala
@@ -35,21 +35,22 @@ trait FileUtils {
     createTempDirForPrefix(prefix)
   }
 
+
+  @SuppressWarnings(Array("org.wartremover.warts.Recursion"))
+  def deleteRecursive(dir: java.io.File): Unit = {
+    for (file <- dir.listFiles) {
+      if (!file.getName.startsWith(".")) {
+        if (file.isDirectory) deleteRecursive(file)
+        file.delete()
+      }
+    }
+  }
+
   /**
     * Recursively remove all files and directories in `root`
     */
   def remove(root: Path): Unit = {
-    Files.walkFileTree(root, new SimpleFileVisitor[Path] {
-      override def visitFile(file: Path, attrs: BasicFileAttributes): FileVisitResult = {
-        Files.delete(file)
-        FileVisitResult.CONTINUE
-      }
-
-      override def postVisitDirectory(dir: Path, exc: IOException): FileVisitResult = {
-        Files.delete(dir)
-        FileVisitResult.CONTINUE
-      }
-    })
+    deleteRecursive(root.toFile)
   }
 
   private def createTempDirForPrefix(prefix: String): java.io.File = {