diff --git a/core/src/darwinMain/kotlin/io/islandtime/format/DateTimeTextProvider.kt b/core/src/darwinMain/kotlin/io/islandtime/format/DateTimeTextProvider.kt
index 044d4c787..60c896f5f 100644
--- a/core/src/darwinMain/kotlin/io/islandtime/format/DateTimeTextProvider.kt
+++ b/core/src/darwinMain/kotlin/io/islandtime/format/DateTimeTextProvider.kt
@@ -8,7 +8,6 @@ import platform.Foundation.NSCalendar
 import platform.Foundation.NSCalendarIdentifierISO8601
 import kotlin.native.concurrent.Worker
 
-@SharedImmutable
 private val worker = Worker.start(errorReporting = false)
 
 actual object PlatformDateTimeTextProvider : DateTimeTextProvider {
diff --git a/core/src/darwinMain/kotlin/io/islandtime/internal/Concurrency.kt b/core/src/darwinMain/kotlin/io/islandtime/internal/Concurrency.kt
index b8011cc1f..bcb707372 100644
--- a/core/src/darwinMain/kotlin/io/islandtime/internal/Concurrency.kt
+++ b/core/src/darwinMain/kotlin/io/islandtime/internal/Concurrency.kt
@@ -3,8 +3,6 @@ package io.islandtime.internal
 import kotlinx.cinterop.StableRef
 import kotlin.native.concurrent.TransferMode
 import kotlin.native.concurrent.Worker
-import kotlin.native.concurrent.ensureNeverFrozen
-import kotlin.native.concurrent.freeze
 
 internal class WorkerConfined<T : Any>(
     private val worker: Worker,
@@ -20,7 +18,7 @@ internal value class ConfinedValueRef<T : Any>(private val value: StableRef<T>)
 
     companion object {
         fun <T : Any> create(value: T): ConfinedValueRef<T> {
-            return ConfinedValueRef(StableRef.create(value.apply { ensureNeverFrozen() }))
+            return ConfinedValueRef(StableRef.create(value))
         }
     }
 }
@@ -43,13 +41,12 @@ private inline fun <T> runOn(worker: Worker, crossinline block: () -> T): T {
 private fun <T> Worker.executeImmediately(block: () -> T): T {
     return execute(
         TransferMode.SAFE,
-        { block.freeze() },
-        {
-            try {
-                Result.success(it())
-            } catch (e: Throwable) {
-                Result.failure(e)
-            }.freeze()
+        { block }
+    ) {
+        try {
+            Result.success(it())
+        } catch (e: Throwable) {
+            Result.failure(e)
         }
-    ).result.getOrThrow()
+    }.result.getOrThrow()
 }
diff --git a/core/src/darwinMain/kotlin/io/islandtime/zone/TimeZoneRules.kt b/core/src/darwinMain/kotlin/io/islandtime/zone/TimeZoneRules.kt
index b6d0dde7a..4c24efb43 100644
--- a/core/src/darwinMain/kotlin/io/islandtime/zone/TimeZoneRules.kt
+++ b/core/src/darwinMain/kotlin/io/islandtime/zone/TimeZoneRules.kt
@@ -18,7 +18,6 @@ import kotlinx.cinterop.convert
 import platform.Foundation.*
 import kotlin.native.concurrent.Worker
 
-@SharedImmutable
 private val worker = Worker.start(errorReporting = false)
 
 /**
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index fe83b3b23..30a64e000 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,5 +1,5 @@
 [versions]
-kotlin = "1.7.10"
+kotlin = "1.7.20"
 dokka = "1.7.10"
 serialization = "1.4.0"
 atomicfu = "0.18.3"