diff --git a/akka-actor/src/main/scala/akka/actor/ActorSystem.scala b/akka-actor/src/main/scala/akka/actor/ActorSystem.scala
index aa1577058d..38813be899 100644
--- a/akka-actor/src/main/scala/akka/actor/ActorSystem.scala
+++ b/akka-actor/src/main/scala/akka/actor/ActorSystem.scala
@@ -13,6 +13,7 @@ import akka.dispatch._
 import akka.japi.Util.immutableSeq
 import akka.actor.dungeon.ChildrenContainer
 import akka.util._
+import akka.util.Helpers.toRootLowerCase
 import scala.annotation.tailrec
 import scala.collection.immutable
 import scala.concurrent.duration.{ Duration }
@@ -180,7 +181,7 @@ object ActorSystem {
     final val LoggingFilter: String = getString("akka.logging-filter")
     final val LoggerStartTimeout: Timeout = Timeout(config.getMillisDuration("akka.logger-startup-timeout"))
     final val LogConfigOnStart: Boolean = config.getBoolean("akka.log-config-on-start")
-    final val LogDeadLetters: Int = config.getString("akka.log-dead-letters").toLowerCase(Locale.ROOT) match {
+    final val LogDeadLetters: Int = toRootLowerCase(config.getString("akka.log-dead-letters")) match {
       case "off" | "false" ⇒ 0
       case "on" | "true"   ⇒ Int.MaxValue
       case _               ⇒ config.getInt("akka.log-dead-letters")
diff --git a/akka-actor/src/main/scala/akka/event/Logging.scala b/akka-actor/src/main/scala/akka/event/Logging.scala
index de95d0aaa0..587f31c0c6 100644
--- a/akka-actor/src/main/scala/akka/event/Logging.scala
+++ b/akka-actor/src/main/scala/akka/event/Logging.scala
@@ -11,6 +11,7 @@ import akka.actor.ActorSystem.Settings
 import akka.actor._
 import akka.dispatch.RequiresMessageQueue
 import akka.util.ReentrantGuard
+import akka.util.Helpers.toRootLowerCase
 import akka.{ AkkaException, ConfigurationException }
 
 import scala.annotation.implicitNotFound
@@ -442,7 +443,7 @@ object Logging {
    * valid inputs are upper or lowercase (not mixed) versions of:
    * "error", "warning", "info" and "debug"
    */
-  def levelFor(s: String): Option[LogLevel] = s.toLowerCase(Locale.ROOT) match {
+  def levelFor(s: String): Option[LogLevel] = toRootLowerCase(s) match {
     case "off"     ⇒ Some(OffLevel)
     case "error"   ⇒ Some(ErrorLevel)
     case "warning" ⇒ Some(WarningLevel)
diff --git a/akka-actor/src/main/scala/akka/util/Helpers.scala b/akka-actor/src/main/scala/akka/util/Helpers.scala
index d4318f09a1..bd9add550b 100644
--- a/akka-actor/src/main/scala/akka/util/Helpers.scala
+++ b/akka-actor/src/main/scala/akka/util/Helpers.scala
@@ -14,7 +14,9 @@ import java.util.Locale
 
 object Helpers {
 
-  val isWindows: Boolean = System.getProperty("os.name", "").toLowerCase(Locale.ROOT).indexOf("win") >= 0
+  def toRootLowerCase(s: String) = s.toLowerCase(Locale.ROOT)
+
+  val isWindows: Boolean = toRootLowerCase(System.getProperty("os.name", "")).indexOf("win") >= 0
 
   def makePattern(s: String): Pattern = Pattern.compile("^\\Q" + s.replace("?", "\\E.\\Q").replace("*", "\\E.*\\Q") + "\\E$")
 
diff --git a/akka-cluster/src/main/scala/akka/cluster/ClusterSettings.scala b/akka-cluster/src/main/scala/akka/cluster/ClusterSettings.scala
index 711e7de8da..ed9731de03 100644
--- a/akka-cluster/src/main/scala/akka/cluster/ClusterSettings.scala
+++ b/akka-cluster/src/main/scala/akka/cluster/ClusterSettings.scala
@@ -11,8 +11,7 @@ import scala.concurrent.duration.Duration
 import akka.actor.Address
 import akka.actor.AddressFromURIString
 import akka.dispatch.Dispatchers
-import akka.util.Helpers.Requiring
-import akka.util.Helpers.ConfigOps
+import akka.util.Helpers.{Requiring, ConfigOps, toRootLowerCase}
 
 import scala.concurrent.duration.FiniteDuration
 import akka.japi.Util.immutableSeq
@@ -40,7 +39,7 @@ final class ClusterSettings(val config: Config, val systemName: String) {
   val SeedNodeTimeout: FiniteDuration = cc.getMillisDuration("seed-node-timeout")
   val RetryUnsuccessfulJoinAfter: Duration = {
     val key = "retry-unsuccessful-join-after"
-    cc.getString(key).toLowerCase(Locale.ROOT) match {
+    toRootLowerCase(cc.getString(key)) match {
       case "off" ⇒ Duration.Undefined
       case _     ⇒ cc.getMillisDuration(key) requiring (_ > Duration.Zero, key + " > 0s, or off")
     }
@@ -54,7 +53,7 @@ final class ClusterSettings(val config: Config, val systemName: String) {
   val UnreachableNodesReaperInterval: FiniteDuration = cc.getMillisDuration("unreachable-nodes-reaper-interval")
   val PublishStatsInterval: Duration = {
     val key = "publish-stats-interval"
-    cc.getString(key).toLowerCase(Locale.ROOT) match {
+    toRootLowerCase(cc.getString(key)) match {
       case "off" ⇒ Duration.Undefined
       case _     ⇒ cc.getMillisDuration(key) requiring (_ >= Duration.Zero, key + " >= 0s, or off")
     }
@@ -63,7 +62,7 @@ final class ClusterSettings(val config: Config, val systemName: String) {
   // specific to the [[akka.cluster.DefaultDowningProvider]]
   val AutoDownUnreachableAfter: Duration = {
     val key = "auto-down-unreachable-after"
-    cc.getString(key).toLowerCase(Locale.ROOT) match {
+    toRootLowerCase(cc.getString(key)) match {
       case "off" ⇒ Duration.Undefined
       case _     ⇒ cc.getMillisDuration(key) requiring (_ >= Duration.Zero, key + " >= 0s, or off")
     }
@@ -77,7 +76,7 @@ final class ClusterSettings(val config: Config, val systemName: String) {
   @deprecated("Use Cluster.downingProvider.downRemovalMargin", since = "2.4.5")
   val DownRemovalMargin: FiniteDuration = {
     val key = "down-removal-margin"
-    cc.getString(key).toLowerCase(Locale.ROOT) match {
+    toRootLowerCase(cc.getString(key)) match {
       case "off" ⇒ Duration.Zero
       case _     ⇒ cc.getMillisDuration(key) requiring (_ >= Duration.Zero, key + " >= 0s, or off")
     }
diff --git a/akka-persistence/src/main/scala/akka/persistence/journal/AsyncWriteJournal.scala b/akka-persistence/src/main/scala/akka/persistence/journal/AsyncWriteJournal.scala
index 9e067c70be..417d20f565 100644
--- a/akka-persistence/src/main/scala/akka/persistence/journal/AsyncWriteJournal.scala
+++ b/akka-persistence/src/main/scala/akka/persistence/journal/AsyncWriteJournal.scala
@@ -9,6 +9,7 @@ import scala.concurrent.duration._
 import akka.actor._
 import akka.pattern.pipe
 import akka.persistence._
+import akka.util.Helpers.toRootLowerCase
 import scala.collection.immutable
 import scala.concurrent.Future
 import scala.util.{ Failure, Success, Try }
@@ -36,7 +37,7 @@ trait AsyncWriteJournal extends Actor with WriteJournalBase with AsyncRecovery {
   }
 
   private val replayFilterMode: ReplayFilter.Mode =
-    config.getString("replay-filter.mode").toLowerCase(Locale.ROOT) match {
+    toRootLowerCase(config.getString("replay-filter.mode")) match {
       case "off"                   ⇒ ReplayFilter.Disabled
       case "repair-by-discard-old" ⇒ ReplayFilter.RepairByDiscardOld
       case "fail"                  ⇒ ReplayFilter.Fail
diff --git a/akka-remote/src/main/scala/akka/remote/RemoteSettings.scala b/akka-remote/src/main/scala/akka/remote/RemoteSettings.scala
index f6138bb5fb..5638ac1806 100644
--- a/akka-remote/src/main/scala/akka/remote/RemoteSettings.scala
+++ b/akka-remote/src/main/scala/akka/remote/RemoteSettings.scala
@@ -7,8 +7,7 @@ import com.typesafe.config.Config
 import scala.concurrent.duration._
 import akka.util.Timeout
 import scala.collection.immutable
-import akka.util.Helpers.ConfigOps
-import akka.util.Helpers.Requiring
+import akka.util.Helpers.{ConfigOps, Requiring, toRootLowerCase}
 import akka.japi.Util._
 import akka.actor.Props
 import akka.event.Logging
@@ -29,7 +28,7 @@ final class RemoteSettings(val config: Config) {
   val TrustedSelectionPaths: Set[String] =
     immutableSeq(getStringList("akka.remote.trusted-selection-paths")).toSet
 
-  val RemoteLifecycleEventsLogLevel: LogLevel = getString("akka.remote.log-remote-lifecycle-events").toLowerCase(Locale.ROOT) match {
+  val RemoteLifecycleEventsLogLevel: LogLevel = toRootLowerCase(getString("akka.remote.log-remote-lifecycle-events")) match {
     case "on" ⇒ Logging.DebugLevel
     case other ⇒ Logging.levelFor(other) match {
       case Some(level) ⇒ level
diff --git a/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala b/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
index 00211faec2..4f06227db3 100644
--- a/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
+++ b/akka-stream/src/main/scala/akka/stream/ActorMaterializer.scala
@@ -9,6 +9,7 @@ import java.util.concurrent.atomic.{ AtomicBoolean }
 
 import akka.actor.{ ActorContext, ActorRef, ActorRefFactory, ActorSystem, ExtendedActorSystem, Props }
 import akka.event.LoggingAdapter
+import akka.util.Helpers.toRootLowerCase
 import akka.stream.ActorMaterializerSettings.defaultMaxFixedBufferSize
 import akka.stream.impl._
 import com.typesafe.config.Config
@@ -477,7 +478,7 @@ object StreamSubscriptionTimeoutSettings {
   def apply(config: Config): StreamSubscriptionTimeoutSettings = {
     val c = config.getConfig("subscription-timeout")
     StreamSubscriptionTimeoutSettings(
-      mode = c.getString("mode").toLowerCase(Locale.ROOT) match {
+      mode = toRootLowerCase(c.getString("mode")) match {
         case "no" | "off" | "false" | "noop" ⇒ NoopTermination
         case "warn"                          ⇒ WarnTermination
         case "cancel"                        ⇒ CancelTermination