diff --git a/arrow-libs/core/arrow-atomic/build.gradle.kts b/arrow-libs/core/arrow-atomic/build.gradle.kts
index a3d499df493..1fe23d392b5 100644
--- a/arrow-libs/core/arrow-atomic/build.gradle.kts
+++ b/arrow-libs/core/arrow-atomic/build.gradle.kts
@@ -1,13 +1,8 @@
-import org.jetbrains.kotlin.gradle.ExperimentalKotlinGradlePluginApi
-
 plugins {
   id("arrow.kotlin")
 }
 
 kotlin {
-  @OptIn(ExperimentalKotlinGradlePluginApi::class)
-  compilerOptions.freeCompilerArgs.add("-Xexpect-actual-classes")
-
   sourceSets {
     commonTest {
       dependencies {
diff --git a/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/Atomic.kt b/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/Atomic.kt
deleted file mode 100644
index 1c2b3ac380b..00000000000
--- a/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/Atomic.kt
+++ /dev/null
@@ -1,25 +0,0 @@
-package arrow.atomic
-
-public actual class Atomic<V> actual constructor(initialValue: V) {
-  private var internalValue: V = initialValue
-
-  public actual fun get(): V = internalValue
-
-  public actual fun set(value: V) {
-    internalValue = value
-  }
-
-  public actual fun compareAndSet(expected: V, new: V): Boolean =
-    if (expected === internalValue) {
-      internalValue = new
-      true
-    } else {
-      false
-    }
-
-  public actual fun getAndSet(value: V): V {
-    val old = internalValue
-    internalValue = value
-    return old
-  }
-}
diff --git a/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/AtomicInt.kt b/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/AtomicInt.kt
deleted file mode 100644
index cc2d4825873..00000000000
--- a/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/AtomicInt.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package arrow.atomic
-
-public actual class AtomicInt actual constructor(initialValue: Int) {
-  private var internalValue: Int = initialValue
-
-  public actual fun get(): Int = internalValue
-
-  public actual fun set(newValue: Int) {
-    internalValue = newValue
-  }
-
-  public actual fun addAndGet(delta: Int): Int {
-    internalValue += delta
-    return internalValue
-  }
-
-  public actual fun incrementAndGet(): Int = addAndGet(1)
-
-  public actual fun decrementAndGet(): Int = addAndGet(-1)
-
-  public actual fun compareAndSet(expected: Int, new: Int): Boolean =
-    if (expected == internalValue) {
-      internalValue = new
-      true
-    } else {
-      false
-    }
-
-  public actual fun getAndSet(value: Int): Int {
-    val current = internalValue
-    internalValue = value
-    return current
-  }
-}
diff --git a/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/AtomicLong.kt b/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/AtomicLong.kt
deleted file mode 100644
index 3fed6d455d9..00000000000
--- a/arrow-libs/core/arrow-atomic/src/jsMain/kotlin/arrow/atomic/AtomicLong.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package arrow.atomic
-
-public actual class AtomicLong actual constructor(initialValue: Long) {
-  private var internalValue: Long = initialValue
-
-  public actual fun get(): Long = internalValue
-
-  public actual fun set(newValue: Long) {
-    internalValue = newValue
-  }
-
-  public actual fun addAndGet(delta: Long): Long {
-    internalValue += delta
-    return internalValue
-  }
-
-  public actual fun incrementAndGet(): Long = addAndGet(1)
-
-  public actual fun decrementAndGet(): Long = addAndGet(-1)
-
-  public actual fun compareAndSet(expected: Long, new: Long): Boolean =
-    if (expected == internalValue) {
-      internalValue = new
-      true
-    } else {
-      false
-    }
-
-  public actual fun getAndSet(value: Long): Long {
-    val current = internalValue
-    internalValue = value
-    return current
-  }
-}
diff --git a/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/Atomic.kt b/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/Atomic.kt
deleted file mode 100644
index 117a128b971..00000000000
--- a/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/Atomic.kt
+++ /dev/null
@@ -1,19 +0,0 @@
-package arrow.atomic
-
-import kotlin.concurrent.AtomicReference
-
-public actual class Atomic<V> actual constructor(initialValue: V) {
-  private val inner = AtomicReference(initialValue)
-
-  public actual fun get(): V = inner.value
-
-  public actual fun set(value: V) {
-    inner.value = value
-  }
-
-  public actual fun compareAndSet(expected: V, new: V): Boolean =
-    inner.compareAndSet(expected, new)
-
-  public actual fun getAndSet(value: V): V =
-    inner.getAndSet(value)
-}
diff --git a/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/AtomicInt.kt b/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/AtomicInt.kt
deleted file mode 100644
index 9b3ec716938..00000000000
--- a/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/AtomicInt.kt
+++ /dev/null
@@ -1,28 +0,0 @@
-package arrow.atomic
-
-import kotlin.concurrent.AtomicInt
-
-public actual class AtomicInt actual constructor(initialValue: Int) {
-  private val inner = AtomicInt(initialValue)
-
-  public actual fun get(): Int = inner.value
-
-  public actual fun set(newValue: Int) {
-    inner.value = newValue
-  }
-
-  public actual fun incrementAndGet(): Int =
-    inner.incrementAndGet()
-
-  public actual fun decrementAndGet(): Int =
-    inner.decrementAndGet()
-
-  public actual fun addAndGet(delta: Int): Int =
-    inner.addAndGet(delta)
-
-  public actual fun compareAndSet(expected: Int, new: Int): Boolean =
-    inner.compareAndSet(expected, new)
-
-  public actual fun getAndSet(value: Int): Int =
-    inner.getAndSet(value)
-}
diff --git a/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/AtomicLong.kt b/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/AtomicLong.kt
deleted file mode 100644
index e0d099c1831..00000000000
--- a/arrow-libs/core/arrow-atomic/src/nativeMain/kotlin/arrow/atomic/AtomicLong.kt
+++ /dev/null
@@ -1,29 +0,0 @@
-package arrow.atomic
-
-import kotlin.concurrent.AtomicLong
-
-public actual class AtomicLong actual constructor(initialValue: Long) {
-  private val inner = AtomicLong(initialValue)
-
-  public actual fun get(): Long = inner.value
-
-  public actual fun set(newValue: Long) {
-    inner.value = newValue
-  }
-
-  public actual fun incrementAndGet(): Long =
-    inner.incrementAndGet()
-
-  public actual fun decrementAndGet(): Long =
-    inner.decrementAndGet()
-
-  public actual fun addAndGet(delta: Long): Long =
-    inner.addAndGet(delta)
-
-  public actual fun compareAndSet(expected: Long, new: Long): Boolean =
-    inner.compareAndSet(expected, new)
-
-  public actual fun getAndSet(value: Long): Long =
-    inner.getAndSet(value)
-}
-
diff --git a/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/Atomic.kt b/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/Atomic.kt
new file mode 100644
index 00000000000..367ee0ae82f
--- /dev/null
+++ b/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/Atomic.kt
@@ -0,0 +1,20 @@
+@file:OptIn(ExperimentalAtomicApi::class)
+
+package arrow.atomic
+
+import kotlin.concurrent.atomics.ExperimentalAtomicApi
+import kotlin.concurrent.atomics.AtomicReference as KtAtomicReference
+
+public actual class Atomic<V> actual constructor(initialValue: V) {
+  private val inner = KtAtomicReference(initialValue)
+
+  public actual fun get(): V = inner.load()
+  public actual fun set(value: V) { inner.store(value) }
+  public actual fun getAndSet(value: V): V = inner.exchange(value)
+
+  /**
+   * Compare current value with expected and set to new if they're the same. Note, 'compare' is checking
+   * the actual object id, not 'equals'.
+   */
+  public actual fun compareAndSet(expected: V, new: V): Boolean = inner.compareAndSet(expected, new)
+}
diff --git a/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/AtomicInt.kt b/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/AtomicInt.kt
new file mode 100644
index 00000000000..f12ccb09436
--- /dev/null
+++ b/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/AtomicInt.kt
@@ -0,0 +1,23 @@
+@file:OptIn(ExperimentalAtomicApi::class)
+
+package arrow.atomic
+
+import kotlin.concurrent.atomics.ExperimentalAtomicApi
+import kotlin.concurrent.atomics.decrementAndFetch
+import kotlin.concurrent.atomics.incrementAndFetch
+import kotlin.concurrent.atomics.AtomicInt as KtAtomicInt
+
+public actual class AtomicInt actual constructor(initialValue: Int) {
+  private val inner = KtAtomicInt(initialValue)
+
+  public actual fun get(): Int = inner.load()
+  public actual fun set(newValue: Int) { inner.store(newValue) }
+  public actual fun getAndSet(value: Int): Int = inner.exchange(value)
+
+  public actual fun incrementAndGet(): Int = inner.incrementAndFetch()
+  public actual fun decrementAndGet(): Int = inner.decrementAndFetch()
+
+  public actual fun addAndGet(delta: Int): Int = inner.addAndFetch(delta)
+
+  public actual fun compareAndSet(expected: Int, new: Int): Boolean = inner.compareAndSet(expected, new)
+}
diff --git a/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/AtomicLong.kt b/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/AtomicLong.kt
new file mode 100644
index 00000000000..2e110a7b75c
--- /dev/null
+++ b/arrow-libs/core/arrow-atomic/src/nonJvmMain/kotlin/arrow/atomic/AtomicLong.kt
@@ -0,0 +1,23 @@
+@file:OptIn(ExperimentalAtomicApi::class)
+
+package arrow.atomic
+
+import kotlin.concurrent.atomics.AtomicLong as KtAtomicLong
+import kotlin.concurrent.atomics.ExperimentalAtomicApi
+import kotlin.concurrent.atomics.decrementAndFetch
+import kotlin.concurrent.atomics.incrementAndFetch
+
+public actual class AtomicLong actual constructor(initialValue: Long) {
+  private val inner = KtAtomicLong(initialValue)
+
+  public actual fun get(): Long = inner.load()
+  public actual fun set(newValue: Long) { inner.store(newValue) }
+  public actual fun getAndSet(value: Long): Long = inner.exchange(value)
+
+  public actual fun incrementAndGet(): Long = inner.incrementAndFetch()
+  public actual fun decrementAndGet(): Long = inner.decrementAndFetch()
+
+  public actual fun addAndGet(delta: Long): Long = inner.addAndFetch(delta)
+
+  public actual fun compareAndSet(expected: Long, new: Long): Boolean = inner.compareAndSet(expected, new)
+}
diff --git a/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/Atomic.kt b/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/Atomic.kt
deleted file mode 100644
index 1c2b3ac380b..00000000000
--- a/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/Atomic.kt
+++ /dev/null
@@ -1,25 +0,0 @@
-package arrow.atomic
-
-public actual class Atomic<V> actual constructor(initialValue: V) {
-  private var internalValue: V = initialValue
-
-  public actual fun get(): V = internalValue
-
-  public actual fun set(value: V) {
-    internalValue = value
-  }
-
-  public actual fun compareAndSet(expected: V, new: V): Boolean =
-    if (expected === internalValue) {
-      internalValue = new
-      true
-    } else {
-      false
-    }
-
-  public actual fun getAndSet(value: V): V {
-    val old = internalValue
-    internalValue = value
-    return old
-  }
-}
diff --git a/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/AtomicInt.kt b/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/AtomicInt.kt
deleted file mode 100644
index cc2d4825873..00000000000
--- a/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/AtomicInt.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package arrow.atomic
-
-public actual class AtomicInt actual constructor(initialValue: Int) {
-  private var internalValue: Int = initialValue
-
-  public actual fun get(): Int = internalValue
-
-  public actual fun set(newValue: Int) {
-    internalValue = newValue
-  }
-
-  public actual fun addAndGet(delta: Int): Int {
-    internalValue += delta
-    return internalValue
-  }
-
-  public actual fun incrementAndGet(): Int = addAndGet(1)
-
-  public actual fun decrementAndGet(): Int = addAndGet(-1)
-
-  public actual fun compareAndSet(expected: Int, new: Int): Boolean =
-    if (expected == internalValue) {
-      internalValue = new
-      true
-    } else {
-      false
-    }
-
-  public actual fun getAndSet(value: Int): Int {
-    val current = internalValue
-    internalValue = value
-    return current
-  }
-}
diff --git a/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/AtomicLong.kt b/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/AtomicLong.kt
deleted file mode 100644
index 3fed6d455d9..00000000000
--- a/arrow-libs/core/arrow-atomic/src/wasmJsMain/kotlin/arrow/atomic/AtomicLong.kt
+++ /dev/null
@@ -1,34 +0,0 @@
-package arrow.atomic
-
-public actual class AtomicLong actual constructor(initialValue: Long) {
-  private var internalValue: Long = initialValue
-
-  public actual fun get(): Long = internalValue
-
-  public actual fun set(newValue: Long) {
-    internalValue = newValue
-  }
-
-  public actual fun addAndGet(delta: Long): Long {
-    internalValue += delta
-    return internalValue
-  }
-
-  public actual fun incrementAndGet(): Long = addAndGet(1)
-
-  public actual fun decrementAndGet(): Long = addAndGet(-1)
-
-  public actual fun compareAndSet(expected: Long, new: Long): Boolean =
-    if (expected == internalValue) {
-      internalValue = new
-      true
-    } else {
-      false
-    }
-
-  public actual fun getAndSet(value: Long): Long {
-    val current = internalValue
-    internalValue = value
-    return current
-  }
-}