diff --git a/util/collection/src/main/scala/sbt/PMap.scala b/util/collection/src/main/scala/sbt/PMap.scala
index 51c942112..cf0454fd9 100644
--- a/util/collection/src/main/scala/sbt/PMap.scala
+++ b/util/collection/src/main/scala/sbt/PMap.scala
@@ -52,7 +52,7 @@ object IMap {
       put(k, f(this get k getOrElse init))
 
     def mapValues[V2[_]](f: V ~> V2) =
-      new IMap0[K, V2](backing.mapValues(x => f(x)).toMap)
+      new IMap0[K, V2](backing.mapValues(x => f(x)))
 
     def mapSeparate[VL[_], VR[_]](f: V ~> ({ type l[T] = Either[VL[T], VR[T]] })#l) =
       {
diff --git a/util/collection/src/main/scala/sbt/Settings.scala b/util/collection/src/main/scala/sbt/Settings.scala
index 4266af1b6..03173d6ce 100644
--- a/util/collection/src/main/scala/sbt/Settings.scala
+++ b/util/collection/src/main/scala/sbt/Settings.scala
@@ -17,9 +17,9 @@ sealed trait Settings[Scope] {
 }
 
 private final class Settings0[Scope](val data: Map[Scope, AttributeMap], val delegates: Scope => Seq[Scope]) extends Settings[Scope] {
-  def scopes: Set[Scope] = data.keySet.toSet
+  def scopes: Set[Scope] = data.keySet
   def keys(scope: Scope) = data(scope).keys.toSet
-  def allKeys[T](f: (Scope, AttributeKey[_]) => T): Seq[T] = data.flatMap { case (scope, map) => map.keys.map(k => f(scope, k)) } toSeq;
+  def allKeys[T](f: (Scope, AttributeKey[_]) => T): Seq[T] = data.flatMap { case (scope, map) => map.keys.map(k => f(scope, k)) } toSeq
 
   def get[T](scope: Scope, key: AttributeKey[T]): Option[T] =
     delegates(scope).toStream.flatMap(sc => getDirect(sc, key)).headOption
@@ -296,7 +296,7 @@ trait Init[Scope] {
   def definedAtString(settings: Seq[Setting[_]]): String =
     {
       val posDefined = settings.flatMap(_.positionString.toList)
-      if (posDefined.size > 0) {
+      if (posDefined.nonEmpty) {
         val header = if (posDefined.size == settings.size) "defined at:" else
           "some of the defining occurrences:"
         header + (posDefined.distinct mkString ("\n\t", "\n\t", "\n"))
diff --git a/util/complete/src/main/scala/sbt/LineReader.scala b/util/complete/src/main/scala/sbt/LineReader.scala
index 8f9fc219f..b85190f92 100644
--- a/util/complete/src/main/scala/sbt/LineReader.scala
+++ b/util/complete/src/main/scala/sbt/LineReader.scala
@@ -45,7 +45,7 @@ abstract class JLine extends LineReader {
 
   private[this] def handleMultilinePrompt(prompt: String): String = {
     val lines = """\r?\n""".r.split(prompt)
-    lines.size match {
+    lines.length match {
       case 0 | 1 => prompt
       case _     => reader.print(lines.init.mkString("\n") + "\n"); lines.last;
     }
diff --git a/util/log/src/main/scala/sbt/LoggerWriter.scala b/util/log/src/main/scala/sbt/LoggerWriter.scala
index 0165676f5..bc6062563 100644
--- a/util/log/src/main/scala/sbt/LoggerWriter.scala
+++ b/util/log/src/main/scala/sbt/LoggerWriter.scala
@@ -17,7 +17,7 @@ class LoggerWriter(delegate: Logger, unbufferedLevel: Option[Level.Value], nl: S
   override def close() = flush()
   override def flush(): Unit =
     synchronized {
-      if (buffer.length > 0) {
+      if (buffer.nonEmpty) {
         log(buffer.toString)
         buffer.clear()
       }
diff --git a/util/relation/src/main/scala/sbt/Relation.scala b/util/relation/src/main/scala/sbt/Relation.scala
index 987aafb14..9a648ad64 100644
--- a/util/relation/src/main/scala/sbt/Relation.scala
+++ b/util/relation/src/main/scala/sbt/Relation.scala
@@ -123,7 +123,7 @@ private final class MRelation[A, B](fwd: Map[A, Set[B]], rev: Map[B, Set[A]]) ex
   def _1s = fwd.keySet
   def _2s = rev.keySet
 
-  def size = (fwd.valuesIterator map { _.size }).foldLeft(0)(_ + _)
+  def size = (fwd.valuesIterator map (_.size)).sum
 
   def all: Traversable[(A, B)] = fwd.iterator.flatMap { case (a, bs) => bs.iterator.map(b => (a, b)) }.toTraversable