diff --git a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala
index 564f9812f3..f5685c89f8 100755
--- a/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala
+++ b/akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala
@@ -7,6 +7,7 @@ package akka.cluster.sharding
 import java.net.URLEncoder
 import java.util.Optional
 import java.util.concurrent.ConcurrentHashMap
+import java.util.function.{ Function ⇒ JFunc }
 
 import scala.collection.JavaConverters._
 import scala.collection.immutable
@@ -157,6 +158,7 @@ object ClusterSharding extends ExtensionId[ClusterSharding] with ExtensionIdProv
  * @see [[ClusterSharding$ ClusterSharding companion object]]
  */
 class ClusterSharding(system: ExtendedActorSystem) extends Extension {
+
   import ClusterShardingGuardian._
   import ShardCoordinator.LeastShardAllocationStrategy
   import ShardCoordinator.ShardAllocationStrategy
@@ -229,16 +231,18 @@ class ClusterSharding(system: ExtendedActorSystem) extends Extension {
     handOffStopMessage: Any): ActorRef = {
 
     if (settings.shouldHostShard(cluster)) {
+      regions.computeIfAbsent(typeName, new JFunc[String, ActorRef] {
+        def apply(typeName: String): ActorRef = {
+          implicit val timeout = system.settings.CreationTimeout
+          val startMsg = Start(typeName, entityProps, settings,
+            extractEntityId, extractShardId, allocationStrategy, handOffStopMessage)
+          val Started(shardRegion) = Await.result(guardian ? startMsg, timeout.duration)
+          shardRegion
+        }
+      })
 
-      implicit val timeout = system.settings.CreationTimeout
-      val startMsg = Start(typeName, entityProps, settings,
-        extractEntityId, extractShardId, allocationStrategy, handOffStopMessage)
-      val Started(shardRegion) = Await.result(guardian ? startMsg, timeout.duration)
-      regions.put(typeName, shardRegion)
-      shardRegion
     } else {
       log.debug("Starting Shard Region Proxy [{}] (no actors will be hosted on this node)...", typeName)
-
       startProxy(
         typeName,
         settings.role,
@@ -413,14 +417,16 @@ class ClusterSharding(system: ExtendedActorSystem) extends Extension {
     dataCenter:      Option[DataCenter],
     extractEntityId: ShardRegion.ExtractEntityId,
     extractShardId:  ShardRegion.ExtractShardId): ActorRef = {
-
-    implicit val timeout = system.settings.CreationTimeout
-    val settings = ClusterShardingSettings(system).withRole(role)
-    val startMsg = StartProxy(typeName, dataCenter, settings, extractEntityId, extractShardId)
-    val Started(shardRegion) = Await.result(guardian ? startMsg, timeout.duration)
     // it must be possible to start several proxies, one per data center
-    proxies.put(proxyName(typeName, dataCenter), shardRegion)
-    shardRegion
+    proxies.computeIfAbsent(proxyName(typeName, dataCenter), new JFunc[String, ActorRef] {
+      def apply(name: String): ActorRef = {
+        implicit val timeout = system.settings.CreationTimeout
+        val settings = ClusterShardingSettings(system).withRole(role)
+        val startMsg = StartProxy(typeName, dataCenter, settings, extractEntityId, extractShardId)
+        val Started(shardRegion) = Await.result(guardian ? startMsg, timeout.duration)
+        shardRegion
+      }
+    })
   }
 
   private def proxyName(typeName: String, dataCenter: Option[DataCenter]): String = {