diff --git a/main-actions/src/main/scala/sbt/Package.scala b/main-actions/src/main/scala/sbt/Package.scala
index 63d39b53a..63f2fa395 100644
--- a/main-actions/src/main/scala/sbt/Package.scala
+++ b/main-actions/src/main/scala/sbt/Package.scala
@@ -6,7 +6,7 @@ package sbt
 import Predef.{ conforms => _, _ }
 import java.io.File
 import java.util.jar.{ Attributes, Manifest }
-import collection.JavaConversions._
+import collection.JavaConverters._
 import sbt.internal.util.Types.:+:
 import sbt.io.syntax._
 import sbt.io.IO
@@ -34,12 +34,12 @@ object Package {
       new ManifestAttributes(converted: _*)
     }
 
-  def mergeAttributes(a1: Attributes, a2: Attributes) = a1 ++= a2
+  def mergeAttributes(a1: Attributes, a2: Attributes) = a1.asScala ++= a2.asScala
   // merges `mergeManifest` into `manifest` (mutating `manifest` in the process)
   def mergeManifests(manifest: Manifest, mergeManifest: Manifest): Unit = {
     mergeAttributes(manifest.getMainAttributes, mergeManifest.getMainAttributes)
-    val entryMap = mapAsScalaMap(manifest.getEntries)
-    for ((key, value) <- mergeManifest.getEntries) {
+    val entryMap = manifest.getEntries.asScala
+    for ((key, value) <- mergeManifest.getEntries.asScala) {
       entryMap.get(key) match {
         case Some(attributes) => mergeAttributes(attributes, value)
         case None             => entryMap put (key, value)
@@ -55,7 +55,7 @@ object Package {
       option match {
         case JarManifest(mergeManifest)          => mergeManifests(manifest, mergeManifest)
         case MainClass(mainClassName)            => main.put(Attributes.Name.MAIN_CLASS, mainClassName)
-        case ManifestAttributes(attributes @ _*) => main ++= attributes
+        case ManifestAttributes(attributes @ _*) => main.asScala ++= attributes
         case _                                   => log.warn("Ignored unknown package option " + option)
       }
     }
diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 0602cd778..47cc86e04 100755
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -1718,10 +1718,10 @@ object Classpaths {
       }
 
   import java.util.LinkedHashSet
-  import collection.JavaConversions.asScalaSet
+  import collection.JavaConverters._
   def interSort(projectRef: ProjectRef, conf: Configuration, data: Settings[Scope], deps: BuildDependencies): Seq[(ProjectRef, String)] =
     {
-      val visited = asScalaSet(new LinkedHashSet[(ProjectRef, String)])
+      val visited = (new LinkedHashSet[(ProjectRef, String)]).asScala
       def visit(p: ProjectRef, c: Configuration): Unit = {
         val applicableConfigs = allConfigs(c)
         for (ac <- applicableConfigs) // add all configurations in this project
@@ -1758,7 +1758,7 @@ object Classpaths {
     track: TrackLevel, includeSelf: Boolean, f: (ProjectRef, String, Settings[Scope], TrackLevel) => Task[Classpath]): Task[Classpath] =
     {
       val visited = interSort(projectRef, conf, data, deps)
-      val tasks = asScalaSet(new LinkedHashSet[Task[Classpath]])
+      val tasks = (new LinkedHashSet[Task[Classpath]]).asScala
       for ((dep, c) <- visited)
         if (includeSelf || (dep != projectRef) || (conf.name != c && self.name != c))
           tasks += f(dep, c, data, track)
diff --git a/main/src/main/scala/sbt/internal/PluginDiscovery.scala b/main/src/main/scala/sbt/internal/PluginDiscovery.scala
index 426c82bec..f4f06d7ab 100644
--- a/main/src/main/scala/sbt/internal/PluginDiscovery.scala
+++ b/main/src/main/scala/sbt/internal/PluginDiscovery.scala
@@ -112,8 +112,8 @@ object PluginDiscovery {
    */
   def binaryModuleNames(classpath: Seq[File], loader: ClassLoader, resourceName: String): Seq[String] =
     {
-      import collection.JavaConversions._
-      loader.getResources(resourceName).toSeq.filter(onClasspath(classpath)) flatMap { u =>
+      import collection.JavaConverters._
+      loader.getResources(resourceName).asScala.toSeq.filter(onClasspath(classpath)) flatMap { u =>
         IO.readLinesURL(u).map(_.trim).filter(!_.isEmpty)
       }
     }
diff --git a/main/src/main/scala/sbt/internal/TaskTimings.scala b/main/src/main/scala/sbt/internal/TaskTimings.scala
index 8d4606a33..5a9d8e46d 100644
--- a/main/src/main/scala/sbt/internal/TaskTimings.scala
+++ b/main/src/main/scala/sbt/internal/TaskTimings.scala
@@ -29,9 +29,9 @@ private[sbt] final class TaskTimings extends ExecuteProgress[Task] {
     {
       val total = System.nanoTime - start
       println("Total time: " + (total * 1e-6) + " ms")
-      import collection.JavaConversions._
+      import collection.JavaConverters._
       def sumTimes(in: Seq[(Task[_], Long)]) = in.map(_._2).sum
-      val timingsByName = timings.toSeq.groupBy { case (t, time) => mappedName(t) } mapValues (sumTimes)
+      val timingsByName = timings.asScala.toSeq.groupBy { case (t, time) => mappedName(t) } mapValues (sumTimes)
       for ((taskName, time) <- timingsByName.toSeq.sortBy(_._2).reverse)
         println("  " + taskName + ": " + (time * 1e-6) + " ms")
     }
diff --git a/tasks/src/main/scala/sbt/Execute.scala b/tasks/src/main/scala/sbt/Execute.scala
index aa5e2f7d3..8f03ee557 100644
--- a/tasks/src/main/scala/sbt/Execute.scala
+++ b/tasks/src/main/scala/sbt/Execute.scala
@@ -9,11 +9,12 @@ import sbt.internal.util.Types._
 import Execute._
 
 import scala.annotation.tailrec
-import scala.collection.{ mutable, JavaConversions }
+import scala.collection.mutable
+import scala.collection.JavaConverters._
 import mutable.Map
 
 private[sbt] object Execute {
-  def idMap[A, B]: Map[A, B] = JavaConversions.mapAsScalaMap(new java.util.IdentityHashMap[A, B])
+  def idMap[A, B]: Map[A, B] = (new java.util.IdentityHashMap[A, B]).asScala
   def pMap[A[_], B[_]]: PMap[A, B] = new DelegatingPMap[A, B](idMap)
   private[sbt] def completed(p: => Unit): Completed = new Completed {
     def process(): Unit = p
diff --git a/tasks/src/main/scala/sbt/Incomplete.scala b/tasks/src/main/scala/sbt/Incomplete.scala
index a83e33e36..37484653b 100644
--- a/tasks/src/main/scala/sbt/Incomplete.scala
+++ b/tasks/src/main/scala/sbt/Incomplete.scala
@@ -29,8 +29,8 @@ object Incomplete extends Enumeration {
   def transformBU(i: Incomplete)(f: Incomplete => Incomplete): Incomplete = transform(i, false)(f)
   def transform(i: Incomplete, topDown: Boolean)(f: Incomplete => Incomplete): Incomplete =
     {
-      import collection.JavaConversions._
-      val visited: collection.mutable.Map[Incomplete, Incomplete] = new java.util.IdentityHashMap[Incomplete, Incomplete]
+      import collection.JavaConverters._
+      val visited: collection.mutable.Map[Incomplete, Incomplete] = (new java.util.IdentityHashMap[Incomplete, Incomplete]).asScala
       def visit(inc: Incomplete): Incomplete =
         visited.getOrElseUpdate(inc, if (topDown) visitCauses(f(inc)) else f(visitCauses(inc)))
       def visitCauses(inc: Incomplete): Incomplete =
diff --git a/testing/src/main/scala/sbt/TestStatusReporter.scala b/testing/src/main/scala/sbt/TestStatusReporter.scala
index b1fbf0f84..738b6c6cf 100644
--- a/testing/src/main/scala/sbt/TestStatusReporter.scala
+++ b/testing/src/main/scala/sbt/TestStatusReporter.scala
@@ -29,10 +29,10 @@ private[sbt] object TestStatus {
   import java.util.Properties
   def read(f: File): Map[String, Long] =
     {
-      import scala.collection.JavaConversions.{ propertiesAsScalaMap }
+      import scala.collection.JavaConverters._
       val properties = new Properties
       IO.load(properties, f)
-      properties map { case (k, v) => (k, v.toLong) }
+      properties.asScala map { case (k, v) => (k, v.toLong) }
     }
   def write(map: Map[String, Long], label: String, f: File): Unit = {
     val properties = new Properties