diff --git a/FAQ.md b/FAQ.md
index 0d6cfaf51e5..e8464d4ea63 100644
--- a/FAQ.md
+++ b/FAQ.md
@@ -48,7 +48,7 @@ framework("MyCustomFramework") {
 ### Q: Why do I see `InvalidMutabilityException`?
 
 A: It likely happens, because you are trying to mutate a frozen object. Object could transfer to the
-frozen state either explicitly, as objects reachable from objects on which `konan.worker.freeze` is called,
+frozen state either explicitly, as objects reachable from objects on which `kotlin.native.concurrent.freeze` is called,
 or implicitly (i.e. reachable from `enum` or global singleton object - see next question).
 
 
@@ -56,7 +56,7 @@ or implicitly (i.e. reachable from `enum` or global singleton object - see next
 
 A: Currently, singleton objects are immutable (i.e. frozen after creation), and it's generally considered
 a good practise to have global state immutable. If for some reasons you need mutable state inside such an
-object, use `@konan.ThreadLocal` annotation on the object. Also `konan.worker.AtomicReference` class could be
+object, use `@konan.ThreadLocal` annotation on the object. Also `kotlin.native.concurrent.AtomicReference` class could be
 used to store different pointers to frozen objects in a frozen object and atomically update those.
 
 ### Q: How can I compile my project against Kotlin/Native master?
diff --git a/IMMUTABILITY.md b/IMMUTABILITY.md
index c2080b3c958..4c36a2a946a 100644
--- a/IMMUTABILITY.md
+++ b/IMMUTABILITY.md
@@ -5,7 +5,7 @@ important invariant that object is either immutable or
 accessible from the single thread at the moment (`mutable XOR global`).
 
  Immutability is the runtime property in Kotlin/Native, and can be applied
-to an arbitrary object subgraph using `konan.worker.freeze` function.
+to an arbitrary object subgraph using `kotlin.native.concurrent.freeze` function.
 It makes all objects reachable from the given one immutable, and
 such a transition is a one way operation (object cannot be unfrozen later).
 Some naturally immutable objects, such as `kotlin.String`, `kotlin.Int` and
diff --git a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/InteropUtils.kt b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/InteropUtils.kt
index 1d7f6a89a05..17552a0a0b6 100644
--- a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/InteropUtils.kt
+++ b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/InteropUtils.kt
@@ -79,12 +79,12 @@ internal class InteropBuiltIns(builtIns: KonanBuiltIns, vararg konanPrimitives:
 
     val staticCFunction = packageScope.getContributedFunctions("staticCFunction").toSet()
 
-    val workerPackageScope = builtIns.builtInsModule.getPackage(FqName("kotlin.native.worker")).memberScope
+    val concurrentPackageScope = builtIns.builtInsModule.getPackage(FqName("kotlin.native.concurrent")).memberScope
 
-    val scheduleFunction = workerPackageScope.getContributedClass("Worker")
+    val scheduleFunction = concurrentPackageScope.getContributedClass("Worker")
             .unsubstitutedMemberScope.getContributedFunctions("schedule").single()
 
-    val scheduleImplFunction = workerPackageScope.getContributedFunctions("scheduleImpl").single()
+    val scheduleImplFunction = concurrentPackageScope.getContributedFunctions("scheduleImpl").single()
 
     val signExtend = packageScope.getContributedFunctions("signExtend").single()
 
diff --git a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/Ir.kt b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/Ir.kt
index c37ea8f2c87..63a79f13057 100644
--- a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/Ir.kt
+++ b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/ir/Ir.kt
@@ -297,10 +297,12 @@ internal class KonanSymbols(context: Context, val symbolTable: SymbolTable, val
             context.getInternalFunctions("valueOfForEnum").single())
 
     val enumValues = symbolTable.referenceSimpleFunction(
-             builtInsPackage("kotlin").getContributedFunctions(Name.identifier("enumValues"), NoLookupLocation.FROM_BACKEND).single())
+             builtInsPackage("kotlin").getContributedFunctions(
+                     Name.identifier("enumValues"), NoLookupLocation.FROM_BACKEND).single())
 
     val enumValueOf = symbolTable.referenceSimpleFunction(
-            builtInsPackage("kotlin").getContributedFunctions(Name.identifier("enumValueOf"), NoLookupLocation.FROM_BACKEND).single())
+            builtInsPackage("kotlin").getContributedFunctions(
+                    Name.identifier("enumValueOf"), NoLookupLocation.FROM_BACKEND).single())
 
     val createUninitializedInstance = symbolTable.referenceSimpleFunction(
             context.getInternalFunctions("createUninitializedInstance").single())
@@ -309,14 +311,17 @@ internal class KonanSymbols(context: Context, val symbolTable: SymbolTable, val
             context.getInternalFunctions("initInstance").single())
 
     val freeze = symbolTable.referenceSimpleFunction(
-            builtInsPackage("kotlin", "native", "worker").getContributedFunctions(Name.identifier("freeze"), NoLookupLocation.FROM_BACKEND).single())
+            builtInsPackage("kotlin", "native", "concurrent").getContributedFunctions(
+                    Name.identifier("freeze"), NoLookupLocation.FROM_BACKEND).single())
 
     val println = symbolTable.referenceSimpleFunction(
-            builtInsPackage("kotlin", "io").getContributedFunctions(Name.identifier("println"), NoLookupLocation.FROM_BACKEND)
+            builtInsPackage("kotlin", "io").getContributedFunctions(
+                    Name.identifier("println"), NoLookupLocation.FROM_BACKEND)
                     .single { it.valueParameters.singleOrNull()?.type == builtIns.stringType })
 
     val anyNToString = symbolTable.referenceSimpleFunction(
-            builtInsPackage("kotlin").getContributedFunctions(Name.identifier("toString"), NoLookupLocation.FROM_BACKEND)
+            builtInsPackage("kotlin").getContributedFunctions(
+                    Name.identifier("toString"), NoLookupLocation.FROM_BACKEND)
                     .single { it.extensionReceiverParameter?.type == builtIns.nullableAnyType})
 
     val getContinuation = symbolTable.referenceSimpleFunction(
@@ -350,10 +355,8 @@ internal class KonanSymbols(context: Context, val symbolTable: SymbolTable, val
                     .filterNot { it.isExpect }.single().getter!!
     )
 
-    // removed in Big Kotlin @c62e4b4fcf50e99800e6d5c3a220101b691e1d43
     val refClass = symbolTable.referenceClass(context.getInternalClass("Ref"))
 
-
     val kLocalDelegatedPropertyImpl = symbolTable.referenceClass(context.reflectionTypes.kLocalDelegatedPropertyImpl)
     val kLocalDelegatedMutablePropertyImpl = symbolTable.referenceClass(context.reflectionTypes.kLocalDelegatedMutablePropertyImpl)
 
@@ -376,7 +379,7 @@ internal class KonanSymbols(context: Context, val symbolTable: SymbolTable, val
             symbolTable.referenceClass(context.getInternalClass(name))
 
     private fun getKonanTestClass(className: String) = symbolTable.referenceClass(
-            builtInsPackage("kotlin", "native", "test").getContributedClassifier(
+            builtInsPackage("kotlin", "native", "internal", "test").getContributedClassifier(
                     Name.identifier(className), NoLookupLocation.FROM_BACKEND
             ) as ClassDescriptor)
 
diff --git a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/EntryPoint.kt b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/EntryPoint.kt
index e2900a0ef90..1782f63a466 100644
--- a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/EntryPoint.kt
+++ b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/EntryPoint.kt
@@ -61,7 +61,7 @@ internal fun findMainEntryPoint(context: Context): FunctionDescriptor? {
 }
 
 private val defaultEntryName = "main"
-private val testEntryName = "kotlin.native.test.main"
+private val testEntryName = "kotlin.native.internal.test.main"
 
 private val defaultEntryPackage = FqName.ROOT
 
diff --git a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TestProcessor.kt b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TestProcessor.kt
index eeca9958d81..aef139b4ffa 100644
--- a/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TestProcessor.kt
+++ b/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/lower/TestProcessor.kt
@@ -346,7 +346,7 @@ internal class TestProcessor (val context: KonanBackendContext) {
     }
 
     /**
-     * Builds a method in `[testSuite]` class with anem `[getterName]`
+     * Builds a method in `[testSuite]` class with name `[getterName]`
      * returning a new instance of class referenced by [classSymbol].
      */
     private inner class InstanceGetterBuilder(val classSymbol: IrClassSymbol, testSuite: IrClassSymbol, getterName: Name)
diff --git a/backend.native/tests/codegen/enum/isFrozen.kt b/backend.native/tests/codegen/enum/isFrozen.kt
index a2e6c3ec6a3..630423924d7 100644
--- a/backend.native/tests/codegen/enum/isFrozen.kt
+++ b/backend.native/tests/codegen/enum/isFrozen.kt
@@ -1,7 +1,7 @@
 package codegen.enum.isFrozen
 
 import kotlin.test.*
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 enum class Zzz(val zzz: String) {
     Z1("z1"),
diff --git a/backend.native/tests/runtime/basic/worker_random.kt b/backend.native/tests/runtime/basic/worker_random.kt
index ffdcb7608e4..6fb15a67ca5 100644
--- a/backend.native/tests/runtime/basic/worker_random.kt
+++ b/backend.native/tests/runtime/basic/worker_random.kt
@@ -1,6 +1,6 @@
 package runtime.basic.worker_random
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 import kotlin.collections.*
 import kotlin.random.*
 import kotlin.system.*
diff --git a/backend.native/tests/runtime/workers/atomic0.kt b/backend.native/tests/runtime/workers/atomic0.kt
index f9a3a345216..a81430ff891 100644
--- a/backend.native/tests/runtime/workers/atomic0.kt
+++ b/backend.native/tests/runtime/workers/atomic0.kt
@@ -2,7 +2,7 @@ package runtime.workers.atomic0
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 fun test1(workers: Array<Worker>) {
     val atomic = AtomicInt(15)
diff --git a/backend.native/tests/runtime/workers/enum_identity.kt b/backend.native/tests/runtime/workers/enum_identity.kt
index be3bd1905b0..2cca9e54561 100644
--- a/backend.native/tests/runtime/workers/enum_identity.kt
+++ b/backend.native/tests/runtime/workers/enum_identity.kt
@@ -1,7 +1,7 @@
 package runtime.workers.enum_identity
 
 import kotlin.test.*
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 enum class A {
     A, B
diff --git a/backend.native/tests/runtime/workers/freeze0.kt b/backend.native/tests/runtime/workers/freeze0.kt
index 267faa03197..513ed2691da 100644
--- a/backend.native/tests/runtime/workers/freeze0.kt
+++ b/backend.native/tests/runtime/workers/freeze0.kt
@@ -18,7 +18,7 @@ package runtime.workers.freeze0
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class SharedDataMember(val double: Double)
 
diff --git a/backend.native/tests/runtime/workers/freeze1.kt b/backend.native/tests/runtime/workers/freeze1.kt
index 022373f5fe8..8ff0eda3198 100644
--- a/backend.native/tests/runtime/workers/freeze1.kt
+++ b/backend.native/tests/runtime/workers/freeze1.kt
@@ -18,7 +18,7 @@ package runtime.workers.freeze1
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class Node(var previous: Node?, var data: Int)
 
diff --git a/backend.native/tests/runtime/workers/freeze2.kt b/backend.native/tests/runtime/workers/freeze2.kt
index b3455a794eb..757c387ac85 100644
--- a/backend.native/tests/runtime/workers/freeze2.kt
+++ b/backend.native/tests/runtime/workers/freeze2.kt
@@ -18,7 +18,7 @@ package runtime.workers.freeze2
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class Data(var int: Int)
 
diff --git a/backend.native/tests/runtime/workers/freeze3.kt b/backend.native/tests/runtime/workers/freeze3.kt
index 62d8a1f7489..c752fe290bb 100644
--- a/backend.native/tests/runtime/workers/freeze3.kt
+++ b/backend.native/tests/runtime/workers/freeze3.kt
@@ -2,7 +2,7 @@ package runtime.workers.freeze3
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 object Immutable {
     var x = 1
diff --git a/backend.native/tests/runtime/workers/freeze4.kt b/backend.native/tests/runtime/workers/freeze4.kt
index 4c36e29fcc4..b4be64033f2 100644
--- a/backend.native/tests/runtime/workers/freeze4.kt
+++ b/backend.native/tests/runtime/workers/freeze4.kt
@@ -2,7 +2,7 @@ package runtime.workers.freeze4
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class Data(val x: Int, val s: String, val next: Data? = null)
 
diff --git a/backend.native/tests/runtime/workers/freeze5.kt b/backend.native/tests/runtime/workers/freeze5.kt
index a55e8443a2e..8c155b0f57c 100644
--- a/backend.native/tests/runtime/workers/freeze5.kt
+++ b/backend.native/tests/runtime/workers/freeze5.kt
@@ -1,6 +1,7 @@
 package runtime.workers.freeze5
 
 import kotlin.test.*
+
 object Keys {
     internal val myMap: Map<String, List<String>> = mapOf(
             "val1" to listOf("a1", "a2", "a3"),
diff --git a/backend.native/tests/runtime/workers/freeze_stress.kt b/backend.native/tests/runtime/workers/freeze_stress.kt
index 9932bf2de92..04a1397b472 100644
--- a/backend.native/tests/runtime/workers/freeze_stress.kt
+++ b/backend.native/tests/runtime/workers/freeze_stress.kt
@@ -2,7 +2,7 @@ package runtime.workers.freeze_stress
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 class Random(private var seed: Int) {
     fun next(): Int {
diff --git a/backend.native/tests/runtime/workers/lazy0.kt b/backend.native/tests/runtime/workers/lazy0.kt
index 74296f734d8..444ce8621c4 100644
--- a/backend.native/tests/runtime/workers/lazy0.kt
+++ b/backend.native/tests/runtime/workers/lazy0.kt
@@ -2,7 +2,7 @@ package runtime.workers.lazy0
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class Data(val x: Int, val y: String)
 
diff --git a/backend.native/tests/runtime/workers/lazy1.kt b/backend.native/tests/runtime/workers/lazy1.kt
index f46c2824e09..1967359317b 100644
--- a/backend.native/tests/runtime/workers/lazy1.kt
+++ b/backend.native/tests/runtime/workers/lazy1.kt
@@ -2,7 +2,7 @@ package runtime.workers.lazy1
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 class Leak {
     val leak by lazy { this }
diff --git a/backend.native/tests/runtime/workers/worker0.kt b/backend.native/tests/runtime/workers/worker0.kt
index 4cd56af8be8..5a0c9f69260 100644
--- a/backend.native/tests/runtime/workers/worker0.kt
+++ b/backend.native/tests/runtime/workers/worker0.kt
@@ -2,11 +2,11 @@ package runtime.workers.worker0
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     val worker = startWorker()
-    val future = worker.schedule(TransferMode.CHECKED, { "Input".shallowCopy()}) {
+    val future = worker.schedule(TransferMode.CHECKED, { "Input" }) {
         input -> input + " processed"
     }
     future.consume {
diff --git a/backend.native/tests/runtime/workers/worker1.kt b/backend.native/tests/runtime/workers/worker1.kt
index 0e8a0493b15..acd36c8eb05 100644
--- a/backend.native/tests/runtime/workers/worker1.kt
+++ b/backend.native/tests/runtime/workers/worker1.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker1
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     val COUNT = 5
@@ -10,7 +10,7 @@ import kotlin.native.worker.*
 
     for (attempt in 1 .. 3) {
         val futures = Array(workers.size,
-                { i -> workers[i].schedule(TransferMode.CHECKED, { "$attempt: Input $i".shallowCopy() })
+                { i -> workers[i].schedule(TransferMode.CHECKED, { "$attempt: Input $i" })
                 { input -> input + " processed" }
         })
         futures.forEachIndexed { index, future ->
diff --git a/backend.native/tests/runtime/workers/worker2.kt b/backend.native/tests/runtime/workers/worker2.kt
index b2b2c2cf719..ade57eaa8b8 100644
--- a/backend.native/tests/runtime/workers/worker2.kt
+++ b/backend.native/tests/runtime/workers/worker2.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker2
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class WorkerArgument(val intParam: Int, val stringParam: String)
 data class WorkerResult(val intResult: Int, val stringResult: String)
diff --git a/backend.native/tests/runtime/workers/worker3.kt b/backend.native/tests/runtime/workers/worker3.kt
index 1dc6d69405b..007c1610bc3 100644
--- a/backend.native/tests/runtime/workers/worker3.kt
+++ b/backend.native/tests/runtime/workers/worker3.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker3
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class DataParam(var int: Int)
 data class WorkerArgument(val intParam: Int, val dataParam: DataParam)
diff --git a/backend.native/tests/runtime/workers/worker4.kt b/backend.native/tests/runtime/workers/worker4.kt
index a87eb17252b..9a166b558d3 100644
--- a/backend.native/tests/runtime/workers/worker4.kt
+++ b/backend.native/tests/runtime/workers/worker4.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker4
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     val worker = startWorker()
diff --git a/backend.native/tests/runtime/workers/worker5.kt b/backend.native/tests/runtime/workers/worker5.kt
index 1aeb2600136..c23db9755e4 100644
--- a/backend.native/tests/runtime/workers/worker5.kt
+++ b/backend.native/tests/runtime/workers/worker5.kt
@@ -2,11 +2,11 @@ package runtime.workers.worker5
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     val worker = startWorker()
-    val future = worker.schedule(TransferMode.CHECKED, { "zzz".shallowCopy() }) {
+    val future = worker.schedule(TransferMode.CHECKED, { "zzz" }) {
         input -> input.length
     }
     future.consume {
diff --git a/backend.native/tests/runtime/workers/worker6.kt b/backend.native/tests/runtime/workers/worker6.kt
index a00fd7b9d67..61a0c425d71 100644
--- a/backend.native/tests/runtime/workers/worker6.kt
+++ b/backend.native/tests/runtime/workers/worker6.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker6
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     val worker = startWorker()
diff --git a/backend.native/tests/runtime/workers/worker7.kt b/backend.native/tests/runtime/workers/worker7.kt
index 1de1fe444ad..dc4bc0c1f67 100644
--- a/backend.native/tests/runtime/workers/worker7.kt
+++ b/backend.native/tests/runtime/workers/worker7.kt
@@ -2,11 +2,11 @@ package runtime.workers.worker7
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     val worker = startWorker()
-    val future = worker.schedule(TransferMode.CHECKED, { "Input".shallowCopy() }) {
+    val future = worker.schedule(TransferMode.CHECKED, { "Input" }) {
         input -> println(input)
     }
     future.consume {
diff --git a/backend.native/tests/runtime/workers/worker8.kt b/backend.native/tests/runtime/workers/worker8.kt
index 29a6ac5987f..064015e7152 100644
--- a/backend.native/tests/runtime/workers/worker8.kt
+++ b/backend.native/tests/runtime/workers/worker8.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker8
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class SharedDataMember(val double: Double)
 
diff --git a/backend.native/tests/runtime/workers/worker9.kt b/backend.native/tests/runtime/workers/worker9.kt
index c9bd51d52a0..6743519cc05 100644
--- a/backend.native/tests/runtime/workers/worker9.kt
+++ b/backend.native/tests/runtime/workers/worker9.kt
@@ -2,7 +2,7 @@ package runtime.workers.worker9
 
 import kotlin.test.*
 
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 @Test fun runTest() {
     withLock { println("zzz") }
diff --git a/backend.native/tests/testing/annotations.kt b/backend.native/tests/testing/annotations.kt
index 5e4afc4260f..6b8809b466a 100644
--- a/backend.native/tests/testing/annotations.kt
+++ b/backend.native/tests/testing/annotations.kt
@@ -1,8 +1,7 @@
 package kotlin.test.tests
 
 import kotlin.test.*
-import kotlin.native.test.*
-
+import kotlin.native.internal.test.*
 
 @Ignore
 class IgnoredClass {
diff --git a/backend.native/tests/testing/custom_main.kt b/backend.native/tests/testing/custom_main.kt
index ef8a554d1d3..b4e1e067ad9 100644
--- a/backend.native/tests/testing/custom_main.kt
+++ b/backend.native/tests/testing/custom_main.kt
@@ -1,7 +1,7 @@
 package kotlin.test.tests
 
 import kotlin.test.*
-import kotlin.native.test.*
+import kotlin.native.internal.test.*
 
 @Test
 fun test() {
diff --git a/runtime/src/main/cpp/Worker.cpp b/runtime/src/main/cpp/Worker.cpp
index 6dd364a1c92..c5a04ba15b6 100644
--- a/runtime/src/main/cpp/Worker.cpp
+++ b/runtime/src/main/cpp/Worker.cpp
@@ -415,25 +415,6 @@ KInt schedule(KInt id, KInt transferMode, KRef producer, KNativePtr jobFunction)
   return future->id();
 }
 
-OBJ_GETTER(shallowCopy, KConstRef object) {
-  if (object == nullptr) RETURN_OBJ(nullptr);
-
-  const TypeInfo* typeInfo = object->type_info();
-  bool isArray = typeInfo->instanceSize_ < 0;
-  KRef result = isArray ?
-      AllocArrayInstance(typeInfo, object->array()->count_, OBJ_RESULT) :
-      AllocInstance(typeInfo, OBJ_RESULT);
-  // TODO: what to do when object references exist.
-  if (isArray) {
-    RuntimeAssert(object->array()->count_ == 0 || typeInfo != theArrayTypeInfo, "Object array copy unimplemented");
-    memcpy(result->array() + 1, object->array() + 1, ArrayDataSizeBytes(object->array()));
-  } else {
-    RuntimeAssert(typeInfo->objOffsetsCount_ == 0, "Object reference copy unimplemented");
-    memcpy(result + 1, object + 1, typeInfo->instanceSize_);
-  }
-  return result;
-}
-
 KInt stateOfFuture(KInt id) {
   return theState()->stateOfFutureUnlocked(id);
 }
@@ -477,11 +458,6 @@ KInt startWorker() {
   return -1;
 }
 
-OBJ_GETTER(shallowCopy, KConstRef object) {
-  ThrowWorkerUnsupported();
-  RETURN_OBJ(nullptr);
-}
-
 KInt stateOfFuture(KInt id) {
   ThrowWorkerUnsupported();
   return 0;
@@ -540,10 +516,6 @@ KInt Kotlin_Worker_scheduleInternal(KInt id, KInt transferMode, KRef producer, K
   return schedule(id, transferMode, producer, job);
 }
 
-OBJ_GETTER(Kotlin_Worker_shallowCopyInternal, KConstRef object) {
-  RETURN_RESULT_OF(shallowCopy, object);
-}
-
 KInt Kotlin_Worker_stateOfFuture(KInt id) {
   return stateOfFuture(id);
 }
diff --git a/runtime/src/main/kotlin/kotlin/BitSet.kt b/runtime/src/main/kotlin/kotlin/BitSet.kt
index df4afb4832e..85fe144bc69 100644
--- a/runtime/src/main/kotlin/kotlin/BitSet.kt
+++ b/runtime/src/main/kotlin/kotlin/BitSet.kt
@@ -19,7 +19,8 @@ package kotlin
 /**
  * A vector of bits growing if necessary and allowing one to set/clear/read bits from it by a bit index.
  */
-class BitSet(size: Int = ELEMENT_SIZE) {
+// TODO: make me internal!
+public class BitSet(size: Int = ELEMENT_SIZE) {
 
     companion object {
         // Size of one element in the array used to store bits.
diff --git a/runtime/src/main/kotlin/kotlin/Lazy.kt b/runtime/src/main/kotlin/kotlin/Lazy.kt
index 20d662822fa..e8dc2e51dfe 100644
--- a/runtime/src/main/kotlin/kotlin/Lazy.kt
+++ b/runtime/src/main/kotlin/kotlin/Lazy.kt
@@ -16,8 +16,9 @@
 
 package kotlin
 
-import kotlin.reflect.KProperty
+import kotlin.native.concurrent.FreezeAwareLazyImpl
 import kotlin.native.internal.FixmeConcurrency
+import kotlin.reflect.KProperty
 
 /**
  * Creates a new instance of the [Lazy] that uses the specified initialization function [initializer]
@@ -28,7 +29,7 @@ import kotlin.native.internal.FixmeConcurrency
  * Note that the returned instance uses itself to synchronize on. Do not synchronize from external code on
  * the returned instance as it may cause accidental deadlock. Also this behavior can be changed in the future.
  */
-public actual fun <T> lazy(initializer: () -> T): Lazy<T> = kotlin.native.worker.FreezeAwareLazyImpl(initializer)
+public actual fun <T> lazy(initializer: () -> T): Lazy<T> = FreezeAwareLazyImpl(initializer)
 
 /**
  * Creates a new instance of the [Lazy] that uses the specified initialization function [initializer]
diff --git a/runtime/src/main/kotlin/kotlin/Primitives.kt b/runtime/src/main/kotlin/kotlin/Primitives.kt
index 0fadb25c5a5..134fff37d12 100644
--- a/runtime/src/main/kotlin/kotlin/Primitives.kt
+++ b/runtime/src/main/kotlin/kotlin/Primitives.kt
@@ -1182,7 +1182,8 @@ public final class Float private constructor(private val value: kotlin.native.in
     }
 
     @SymbolName("Kotlin_Float_bits")
-    external public fun bits(): Int
+    @PublishedApi
+    external internal fun bits(): Int
 }
 
 /**
@@ -1398,10 +1399,11 @@ public final class Double private constructor(private val value: kotlin.native.i
 
     public override fun equals(other: Any?): Boolean = other is Double && this.equals(other)
 
-    public override fun toString() = NumberConverter.convert(this)
+    public override fun toString(): String = NumberConverter.convert(this)
 
     public override fun hashCode(): Int = bits().hashCode()
 
     @SymbolName("Kotlin_Double_bits")
-    external public fun bits(): Long
+    @PublishedApi
+    external internal fun bits(): Long
 }
diff --git a/runtime/src/main/kotlin/kotlin/collections/HashMap.kt b/runtime/src/main/kotlin/kotlin/collections/HashMap.kt
index 8154ab8db41..cd8982d4396 100644
--- a/runtime/src/main/kotlin/kotlin/collections/HashMap.kt
+++ b/runtime/src/main/kotlin/kotlin/collections/HashMap.kt
@@ -16,7 +16,7 @@
 
 package kotlin.collections
 
-import kotlin.native.worker.isFrozen
+import kotlin.native.concurrent.isFrozen
 
 actual class HashMap<K, V> private constructor(
         private var keysArray: Array<K>,
diff --git a/runtime/src/main/kotlin/kotlin/collections/IntUtil.kt b/runtime/src/main/kotlin/kotlin/collections/IntUtil.kt
index bf83cd20092..69bb221a160 100644
--- a/runtime/src/main/kotlin/kotlin/collections/IntUtil.kt
+++ b/runtime/src/main/kotlin/kotlin/collections/IntUtil.kt
@@ -16,7 +16,7 @@
 
 package kotlin.collections
 
-fun Int.highestOneBit() : Int {
+internal fun Int.highestOneBit() : Int {
     var index = 31
 
     while (index >= 0) {
@@ -29,7 +29,7 @@ fun Int.highestOneBit() : Int {
     return 0
 }
 
-fun Int.numberOfLeadingZeros() : Int {
+internal fun Int.numberOfLeadingZeros() : Int {
     var index = 31
 
     while (index >= 0) {
diff --git a/runtime/src/main/kotlin/kotlin/jvm/JvmAnnotations.kt b/runtime/src/main/kotlin/kotlin/jvm/JvmAnnotations.kt
index 28cba3390e4..7387d71f116 100644
--- a/runtime/src/main/kotlin/kotlin/jvm/JvmAnnotations.kt
+++ b/runtime/src/main/kotlin/kotlin/jvm/JvmAnnotations.kt
@@ -27,4 +27,4 @@ actual annotation class JvmMultifileClass
 actual annotation class JvmField
 
 @Target(AnnotationTarget.FIELD)
-actual annotation class Volatile
\ No newline at end of file
+actual annotation class Volatile
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/Atomics.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt
similarity index 99%
rename from runtime/src/main/kotlin/kotlin/native/worker/Atomics.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt
index 3041edc9b7d..435c19fefde 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/Atomics.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlin.native.internal.Frozen
 import kotlin.native.internal.NoReorderFields
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/Freezing.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/Freezing.kt
similarity index 98%
rename from runtime/src/main/kotlin/kotlin/native/worker/Freezing.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/Freezing.kt
index 7012c011236..bffaa4f21a4 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/Freezing.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/Freezing.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlin.native.internal.ExportForCppRuntime
 
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/Future.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/Future.kt
similarity index 86%
rename from runtime/src/main/kotlin/kotlin/native/worker/Future.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/Future.kt
index 4ebd615fba9..cf29b3c5e3b 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/Future.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/Future.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlin.native.SymbolName
 import kotlin.native.internal.ExportForCppRuntime
@@ -40,12 +40,11 @@ enum class FutureState(val value: Int) {
 /**
  * Class representing abstract computation, whose result may become available in the future.
  */
-// TODO: make me value class!
-class Future<T> internal constructor(val id: FutureId) {
+public inline class Future<T>(val id: FutureId) {
     /**
      * Blocks execution until the future is ready.
      */
-    inline fun <R> consume(code: (T) -> R) =
+    public inline fun <R> consume(code: (T) -> R): R =
             when (state) {
                 FutureState.SCHEDULED, FutureState.COMPUTED -> {
                     val value = @Suppress("UNCHECKED_CAST", "NON_PUBLIC_CALL_FROM_PUBLIC_INLINE") (consumeFuture(id) as T)
@@ -57,21 +56,21 @@ class Future<T> internal constructor(val id: FutureId) {
                     throw IllegalStateException("Future is cancelled")
             }
 
-    fun result(): T  = consume { it -> it }
+    public fun result(): T  = consume { it -> it }
 
-    val state: FutureState
+    public val state: FutureState
         get() = FutureState.values()[stateOfFuture(id)]
 
-    override fun equals(other: Any?) = (other is Future<*>) && (id == other.id)
+    public override fun equals(other: Any?): Boolean = (other is Future<*>) && (id == other.id)
 
-    override fun hashCode() = id
+    public override fun hashCode(): Int = id
 }
 
 /**
  * Wait for availability of futures in the collection. Returns set with all futures which have
  * value available for the consumption.
  */
-fun <T> Collection<Future<T>>.waitForMultipleFutures(millis: Int): Set<Future<T>> {
+public fun <T> Collection<Future<T>>.waitForMultipleFutures(millis: Int): Set<Future<T>> {
     val result = mutableSetOf<Future<T>>()
 
     while (true) {
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/Lazy.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/Lazy.kt
similarity index 94%
rename from runtime/src/main/kotlin/kotlin/native/worker/Lazy.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/Lazy.kt
index 0ff3b29e6fd..8bde37d8f23 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/Lazy.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/Lazy.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlin.native.internal.NoReorderFields
 
@@ -65,7 +65,9 @@ internal class FreezeAwareLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
             }
         }
 
-    // Racy!
+    /**
+     * This operation on shared objects may return value which is no longer reflect the current state of lazy.
+     */
     override fun isInitialized(): Boolean = (value_ !== UNINITIALIZED) && (value_ !== INITIALIZING)
 
     override fun toString(): String = if (isInitialized())
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/Lock.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/Lock.kt
similarity index 98%
rename from runtime/src/main/kotlin/kotlin/native/worker/Lock.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/Lock.kt
index 60e9d7bff27..5cf72c9e527 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/Lock.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/Lock.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlin.native.internal.Frozen
 
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/ObjectTransfer.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/ObjectTransfer.kt
similarity index 84%
rename from runtime/src/main/kotlin/kotlin/native/worker/ObjectTransfer.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/ObjectTransfer.kt
index 38f6f877f26..65467c77ed9 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/ObjectTransfer.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/ObjectTransfer.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlinx.cinterop.*
 
@@ -46,17 +46,6 @@ enum class TransferMode(val value: Int) {
     UNCHECKED(1) // USE UNCHECKED MODE ONLY IF ABSOLUTELY SURE WHAT YOU'RE DOING!!!
 }
 
-/**
- * Creates verbatim *shallow* copy of passed object, use carefully to create disjoint object graph.
- */
-inline fun <reified T> T.shallowCopy(): T = shallowCopyInternal(this) as T
-
-/**
- * Creates verbatim *deep* copy of passed object's graph, use *VERY* carefully to create disjoint object graph.
- * Note that this function could potentially duplicate a lot of objects.
- */
-inline fun <reified T> T.deepCopy(): T = TODO()
-
 /**
  * Creates stable pointer to object, ensuring associated object subgraph is disjoint in specified mode
  * ([TransferMode.CHECKED] by default).
@@ -75,11 +64,9 @@ inline fun <reified T> attachObjectGraph(stable: COpaquePointer?): T =
 
 // Private APIs.
 @PublishedApi
-@SymbolName("Kotlin_Worker_shallowCopyInternal")
-external internal fun shallowCopyInternal(value: Any?): Any?
-@PublishedApi
 @SymbolName("Kotlin_Worker_detachObjectGraphInternal")
 external internal fun detachObjectGraphInternal(mode: Int, producer: () -> Any?): COpaquePointer?
+
 @PublishedApi
 @SymbolName("Kotlin_Worker_attachObjectGraphInternal")
 external internal fun attachObjectGraphInternal(stable: COpaquePointer?): Any?
diff --git a/runtime/src/main/kotlin/kotlin/native/worker/Worker.kt b/runtime/src/main/kotlin/kotlin/native/concurrent/Worker.kt
similarity index 90%
rename from runtime/src/main/kotlin/kotlin/native/worker/Worker.kt
rename to runtime/src/main/kotlin/kotlin/native/concurrent/Worker.kt
index 885a6b93644..4dfee584049 100644
--- a/runtime/src/main/kotlin/kotlin/native/worker/Worker.kt
+++ b/runtime/src/main/kotlin/kotlin/native/concurrent/Worker.kt
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package kotlin.native.worker
+package kotlin.native.concurrent
 
 import kotlin.native.SymbolName
 import kotlin.native.internal.ExportForCppRuntime
@@ -42,12 +42,12 @@ typealias WorkerId = Int
  * Class representing worker.
  */
 // TODO: make me value class!
-class Worker(val id: WorkerId) {
+public class Worker(val id: WorkerId) {
     /**
      * Requests termination of the worker. `processScheduledJobs` controls is we shall wait
      * until all scheduled jobs processed, or terminate immediately.
      */
-    fun requestTermination(processScheduledJobs: Boolean = true) =
+    public fun requestTermination(processScheduledJobs: Boolean = true) =
             Future<Nothing?>(requestTerminationInternal(id, processScheduledJobs))
 
     /**
@@ -61,7 +61,7 @@ class Worker(val id: WorkerId) {
      * the future, can use result of worker's computations.
      */
     @Suppress("UNUSED_PARAMETER")
-    fun <T1, T2> schedule(mode: TransferMode, producer: () -> T1, @VolatileLambda job: (T1) -> T2): Future<T2> =
+    public fun <T1, T2> schedule(mode: TransferMode, producer: () -> T1, @VolatileLambda job: (T1) -> T2): Future<T2> =
             /**
              * This function is a magical operation, handled by lowering in the compiler, and replaced with call to
              *   scheduleImpl(worker, mode, producer, job)
@@ -69,9 +69,9 @@ class Worker(val id: WorkerId) {
              */
             throw RuntimeException("Shall not be called directly")
 
-    override fun equals(other: Any?) = (other is Worker) && (id == other.id)
+    override public fun equals(other: Any?): Boolean = (other is Worker) && (id == other.id)
 
-    override fun hashCode() = id
+    override public fun hashCode(): Int = id
 }
 
 /**
@@ -79,7 +79,7 @@ class Worker(val id: WorkerId) {
  * Typically new worker may be needed for computations offload to another core, for IO it may be
  * better to use non-blocking IO combined with more lightweight coroutines.
  */
-fun startWorker(): Worker = Worker(startInternal())
+public fun startWorker(): Worker = Worker(startInternal())
 
 // Private APIs.
 @kotlin.native.internal.ExportForCompiler
diff --git a/runtime/src/main/kotlin/kotlin/native/test/GTestLogger.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/GTestLogger.kt
similarity index 97%
rename from runtime/src/main/kotlin/kotlin/native/test/GTestLogger.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/GTestLogger.kt
index 5d4ad476611..74f8a014853 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/GTestLogger.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/GTestLogger.kt
@@ -14,9 +14,9 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
-class GTestLogger : TestLoggerWithStatistics() {
+internal class GTestLogger : TestLoggerWithStatistics() {
 
     private val Collection<TestSuite>.totalTestsNotIgnored: Int
         get() = asSequence().filter { !it.ignored }.sumBy { it.testCases.values.count { !it.ignored } }
diff --git a/runtime/src/main/kotlin/kotlin/native/test/Launcher.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/Launcher.kt
similarity index 91%
rename from runtime/src/main/kotlin/kotlin/native/test/Launcher.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/Launcher.kt
index 5c5679b6ee9..1b12c15f874 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/Launcher.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/Launcher.kt
@@ -14,14 +14,14 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
 import kotlin.system.exitProcess
 
 @ThreadLocal
 private val _generatedSuites = mutableListOf<TestSuite>()
 
-internal fun registerSuite(suite: TestSuite): Unit {
+public fun registerSuite(suite: TestSuite): Unit {
     _generatedSuites.add(suite)
 }
 
diff --git a/runtime/src/main/kotlin/kotlin/native/test/TeamCityLogger.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/TeamCityLogger.kt
similarity index 96%
rename from runtime/src/main/kotlin/kotlin/native/test/TeamCityLogger.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/TeamCityLogger.kt
index 0ab19abe710..28a6ba241db 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/TeamCityLogger.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/TeamCityLogger.kt
@@ -14,11 +14,11 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
 import kotlin.text.StringBuilder
 
-class TeamCityLogger : BaseTestLogger() {
+internal class TeamCityLogger : BaseTestLogger() {
 
     private fun String.escapeForTC(): String = StringBuilder(length).apply {
         for(char in this@escapeForTC) {
diff --git a/runtime/src/main/kotlin/kotlin/native/test/TestListener.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/TestListener.kt
similarity index 93%
rename from runtime/src/main/kotlin/kotlin/native/test/TestListener.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/TestListener.kt
index c2f2cb009d0..1e9981b445a 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/TestListener.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/TestListener.kt
@@ -14,9 +14,9 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
-interface TestListener {
+internal interface TestListener {
     fun startTesting(runner: TestRunner)
     fun finishTesting(runner: TestRunner, timeMillis: Long)
 
@@ -33,7 +33,7 @@ interface TestListener {
     fun ignore(testCase: TestCase)
 }
 
-open class BaseTestListener: TestListener {
+internal open class BaseTestListener: TestListener {
     override fun startTesting(runner: TestRunner) {}
     override fun finishTesting(runner: TestRunner, timeMillis: Long) {}
     override fun startIteration(runner: TestRunner, iteration: Int, suites: Collection<TestSuite>) {}
diff --git a/runtime/src/main/kotlin/kotlin/native/test/TestLogger.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/TestLogger.kt
similarity index 90%
rename from runtime/src/main/kotlin/kotlin/native/test/TestLogger.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/TestLogger.kt
index dc153a75444..be143cee93f 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/TestLogger.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/TestLogger.kt
@@ -14,14 +14,14 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
-interface TestLogger: TestListener {
+internal interface TestLogger: TestListener {
     fun logTestList(runner: TestRunner, suites: Collection<TestSuite>)
     fun log(message: String)
 }
 
-open class BaseTestLogger: BaseTestListener(), TestLogger {
+internal open class BaseTestLogger: BaseTestListener(), TestLogger {
     override fun log(message: String) = println(message)
     override fun logTestList(runner: TestRunner, suites: Collection<TestSuite>) {
         suites.forEach { suite ->
@@ -33,7 +33,7 @@ open class BaseTestLogger: BaseTestListener(), TestLogger {
     }
 }
 
-open class TestLoggerWithStatistics: BaseTestLogger() {
+internal open class TestLoggerWithStatistics: BaseTestLogger() {
 
     protected val statistics = MutableTestStatistics()
 
@@ -46,13 +46,13 @@ open class TestLoggerWithStatistics: BaseTestLogger() {
     override fun ignore(testCase: TestCase) = statistics.registerIgnore()
 }
 
-class SilentTestLogger: BaseTestLogger() {
+internal class SilentTestLogger: BaseTestLogger() {
     override fun logTestList(runner: TestRunner, suites: Collection<TestSuite>) {}
     override fun log(message: String) {}
     override fun fail(testCase: TestCase, e: Throwable, timeMillis: Long) = e.printStackTrace()
 }
 
-class SimpleTestLogger: BaseTestLogger() {
+internal class SimpleTestLogger: BaseTestLogger() {
     override fun startTesting(runner: TestRunner) = println("Starting testing")
     override fun finishTesting(runner: TestRunner, timeMillis: Long) = println("Testing finished")
 
diff --git a/runtime/src/main/kotlin/kotlin/native/test/TestRunner.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/TestRunner.kt
similarity index 98%
rename from runtime/src/main/kotlin/kotlin/native/test/TestRunner.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/TestRunner.kt
index e4f005f3b80..fdf679cd3f3 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/TestRunner.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/TestRunner.kt
@@ -14,14 +14,14 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
 import kotlin.IllegalArgumentException
 import kotlin.system.getTimeMillis
 import kotlin.system.measureTimeMillis
 import kotlin.text.StringBuilder
 
-class TestRunner(val suites: List<TestSuite>, args: Array<String>) {
+internal class TestRunner(val suites: List<TestSuite>, args: Array<String>) {
     private val filters = mutableListOf<(TestCase) -> Boolean>()
     private val listeners = mutableSetOf<TestListener>()
     private var logger: TestLogger = GTestLogger()
diff --git a/runtime/src/main/kotlin/kotlin/native/test/TestStatistics.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/TestStatistics.kt
similarity index 92%
rename from runtime/src/main/kotlin/kotlin/native/test/TestStatistics.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/TestStatistics.kt
index 4fad74c9f16..77f939d56d9 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/TestStatistics.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/TestStatistics.kt
@@ -14,9 +14,9 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
-interface TestStatistics {
+internal interface TestStatistics {
     val total: Int
     val passed: Int
     val failed: Int
@@ -28,7 +28,7 @@ interface TestStatistics {
     val hasFailedTests: Boolean
 }
 
-class MutableTestStatistics: TestStatistics {
+internal class MutableTestStatistics: TestStatistics {
 
     override var total:   Int = 0; private set
     override var passed:  Int = 0; private set
diff --git a/runtime/src/main/kotlin/kotlin/native/test/TestSuite.kt b/runtime/src/main/kotlin/kotlin/native/internal/test/TestSuite.kt
similarity index 94%
rename from runtime/src/main/kotlin/kotlin/native/test/TestSuite.kt
rename to runtime/src/main/kotlin/kotlin/native/internal/test/TestSuite.kt
index 4dd11d3c437..f102f45900f 100644
--- a/runtime/src/main/kotlin/kotlin/native/test/TestSuite.kt
+++ b/runtime/src/main/kotlin/kotlin/native/internal/test/TestSuite.kt
@@ -14,13 +14,13 @@
  * limitations under the License.
  */
 
-package kotlin.native.test
+package kotlin.native.internal.test
 
 import kotlin.IllegalArgumentException
 import kotlin.system.getTimeMillis
 import kotlin.system.measureTimeMillis
 
-interface TestCase {
+public interface TestCase {
     val name: String
     val ignored: Boolean
     val suite: TestSuite
@@ -30,7 +30,7 @@ interface TestCase {
 
 internal val TestCase.prettyName get() = "${suite.name}.$name"
 
-interface TestSuite {
+public interface TestSuite {
     val name: String
     val ignored: Boolean
     val testCases: Map<String, TestCase>
@@ -40,14 +40,14 @@ interface TestSuite {
     fun doAfterClass()
 }
 
-enum class TestFunctionKind {
+public enum class TestFunctionKind {
     BEFORE_EACH,
     AFTER_EACH,
     BEFORE_CLASS,
     AFTER_CLASS
 }
 
-abstract class AbstractTestSuite<F: Function<Unit>>(override val name: String, override val ignored: Boolean)
+public abstract class AbstractTestSuite<F: Function<Unit>>(override val name: String, override val ignored: Boolean)
     : TestSuite {
     override fun toString(): String = name
 
@@ -80,7 +80,7 @@ abstract class AbstractTestSuite<F: Function<Unit>>(override val name: String, o
         get() = testCases.size
 }
 
-abstract class BaseClassSuite<INSTANCE, COMPANION>(name: String, ignored: Boolean)
+public abstract class BaseClassSuite<INSTANCE, COMPANION>(name: String, ignored: Boolean)
     : AbstractTestSuite<INSTANCE.() -> Unit>(name, ignored) {
 
     class TestCase<INSTANCE, COMPANION>(name: String,
@@ -145,7 +145,7 @@ abstract class BaseClassSuite<INSTANCE, COMPANION>(name: String, ignored: Boolea
 
 private typealias TopLevelFun = () -> Unit
 
-class TopLevelSuite(name: String): AbstractTestSuite<TopLevelFun>(name, false) {
+public class TopLevelSuite(name: String): AbstractTestSuite<TopLevelFun>(name, false) {
 
     class TestCase(name: String, override val suite: TopLevelSuite, testFunction: TopLevelFun, ignored: Boolean)
         : BasicTestCase<TopLevelFun>(name, suite, testFunction, ignored) {
diff --git a/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt b/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt
index c0e6eec3d06..042d5650154 100644
--- a/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt
+++ b/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt
@@ -21,7 +21,7 @@ package kotlin.native.ref
  * retrieve a strong reference to an object, or return null, if object was already destoyed by
  * the memory manager.
  */
-class WeakReference<T : Any> {
+public class WeakReference<T : Any> {
     /**
      * Creates a weak reference object pointing to an object. Weak reference doesn't prevent
      * removing object, and is nullified once object is collected.
@@ -42,9 +42,10 @@ class WeakReference<T : Any> {
     public fun clear() {
         pointer = null
     }
+
+    /**
+     * Returns either reference to an object or null, if it was collected.
+     */
+    public fun get(): T? = pointer?.get() as T?
 }
 
-/**
- * Returns either reference to an object or null, if it was collected.
- */
-public inline fun <reified T : Any> WeakReference<T>.get() = pointer?.get() as T?
diff --git a/runtime/src/main/kotlin/kotlin/random/Random.kt b/runtime/src/main/kotlin/kotlin/random/Random.kt
index 2520a6a6b92..171f2b83483 100644
--- a/runtime/src/main/kotlin/kotlin/random/Random.kt
+++ b/runtime/src/main/kotlin/kotlin/random/Random.kt
@@ -15,7 +15,7 @@
  */
 package kotlin.random
 
-import kotlin.native.worker.AtomicLong
+import kotlin.native.concurrent.AtomicLong
 import kotlin.system.getTimeNanos
 
 abstract class NativeRandom {
diff --git a/runtime/src/main/kotlin/kotlin/text/regex/AbstractCharClass.kt b/runtime/src/main/kotlin/kotlin/text/regex/AbstractCharClass.kt
index 64594df1ee5..298a49f9493 100644
--- a/runtime/src/main/kotlin/kotlin/text/regex/AbstractCharClass.kt
+++ b/runtime/src/main/kotlin/kotlin/text/regex/AbstractCharClass.kt
@@ -33,10 +33,9 @@
 
 package kotlin.text.regex
 
-import kotlin.native.worker.AtomicReference
 import kotlin.collections.associate
-import kotlin.native.worker.freeze
-
+import kotlin.native.concurrent.AtomicReference
+import kotlin.native.concurrent.freeze
 
 /**
  * Unicode category (i.e. Ll, Lu).
diff --git a/samples/globalState/src/main/kotlin/Global.kt b/samples/globalState/src/main/kotlin/Global.kt
index 2c7f48a9ff8..3e62443989c 100644
--- a/samples/globalState/src/main/kotlin/Global.kt
+++ b/samples/globalState/src/main/kotlin/Global.kt
@@ -15,9 +15,10 @@
  */
 
 import global.*
+
+import kotlin.native.concurrent.*
 import kotlinx.cinterop.*
 import platform.posix.*
-import kotlin.native.worker.*
 
 inline fun Int.ensureUnixCallResult(op: String, predicate: (Int) -> Boolean = { x -> x == 0} ): Int {
     if (!predicate(this)) {
@@ -49,7 +50,7 @@ fun main(args: Array<String>) {
     sharedData.f = 0.5f
     sharedData.string = "Hello Kotlin!".cstr.getPointer(arena)
     // Here we create detached mutable object, which could be later reattached by another thread.
-    sharedData.kotlinObject = kotlin.native.worker.detachObjectGraph {
+    sharedData.kotlinObject = detachObjectGraph {
         SharedData("A string", 42, SharedDataMember(2.39))
     }
     // Here we create shared frozen object reference,
@@ -66,12 +67,12 @@ fun main(args: Array<String>) {
             argC ->
             initRuntimeIfNeeded()
             dumpShared("thread2")
-            val kotlinObject = kotlin.native.worker.attachObjectGraph<SharedData>(sharedData.kotlinObject)
-            val arg = kotlin.native.worker.attachObjectGraph<SharedDataMember>(argC)
+            val kotlinObject = attachObjectGraph<SharedData>(sharedData.kotlinObject)
+            val arg = attachObjectGraph<SharedDataMember>(argC)
             println("thread arg is $arg Kotlin object is $kotlinObject frozen is $globalObject")
             // Workaround for compiler issue.
             null as COpaquePointer?
-        }, kotlin.native.worker.detachObjectGraph { SharedDataMember(3.14)} ).ensureUnixCallResult("pthread_create")
+        }, detachObjectGraph { SharedDataMember(3.14)} ).ensureUnixCallResult("pthread_create")
         pthread_join(thread.value, null).ensureUnixCallResult("pthread_join")
     }
 
diff --git a/samples/objc/src/main/kotlin/Window.kt b/samples/objc/src/main/kotlin/Window.kt
index fc19eb3d164..739aee5d6e0 100644
--- a/samples/objc/src/main/kotlin/Window.kt
+++ b/samples/objc/src/main/kotlin/Window.kt
@@ -1,3 +1,5 @@
+import kotlin.native.concurrent.attachObjectGraph
+import kotlin.native.concurrent.detachObjectGraph
 import kotlinx.cinterop.*
 import platform.AppKit.*
 import platform.Foundation.*
@@ -30,12 +32,12 @@ private class Controller : NSObject() {
     @ObjCAction
     fun onClick() {
         // Execute some async action on button click.
-        dispatch_async_f(asyncQueue, kotlin.native.worker.detachObjectGraph {
+        dispatch_async_f(asyncQueue, detachObjectGraph {
             Data(clock_gettime_nsec_np(CLOCK_REALTIME))
         }, staticCFunction {
             it ->
             initRuntimeIfNeeded()
-            val data = kotlin.native.worker.attachObjectGraph<Data>(it)
+            val data = attachObjectGraph<Data>(it)
             println("in async: $data")
         })
     }
diff --git a/samples/videoplayer/src/main/kotlin/DecoderWorker.kt b/samples/videoplayer/src/main/kotlin/DecoderWorker.kt
index 2b60db4afbd..2000444d369 100644
--- a/samples/videoplayer/src/main/kotlin/DecoderWorker.kt
+++ b/samples/videoplayer/src/main/kotlin/DecoderWorker.kt
@@ -15,8 +15,8 @@
  */
 
 import ffmpeg.*
+import kotlin.native.concurrent.*
 import kotlinx.cinterop.*
-import kotlin.native.worker.*
 import platform.posix.memcpy
 
 // This global variable only set to != null value in the decoding worker.
@@ -329,7 +329,7 @@ class DecoderWorker : Disposable {
     // All the real state must be stored on the worker's side.
     private val worker: Worker
 
-    constructor() { worker = kotlin.native.worker.startWorker() }
+    constructor() { worker = startWorker() }
     constructor(id: WorkerId) { worker = Worker(id) }
 
     override fun dispose() {
diff --git a/samples/workers/src/main/kotlin/Workers.kt b/samples/workers/src/main/kotlin/Workers.kt
index 7121b8d03a7..a8d169da7e5 100644
--- a/samples/workers/src/main/kotlin/Workers.kt
+++ b/samples/workers/src/main/kotlin/Workers.kt
@@ -1,4 +1,4 @@
-import kotlin.native.worker.*
+import kotlin.native.concurrent.*
 
 data class WorkerArgument(val intParam: Int, val stringParam: String)
 data class WorkerResult(val intResult: Int, val stringResult: String)