diff --git a/Package.swift b/Package.swift
index a025ff1e86..68d2550c2e 100644
--- a/Package.swift
+++ b/Package.swift
@@ -6,7 +6,7 @@ let package = Package(
   name: "Verge",
   platforms: [
     .macOS(.v11),
-    .iOS(.v16),
+    .iOS(.v13),
     .tvOS(.v13),
     .watchOS(.v6),
   ],
diff --git a/Tests/VergeTests/ConcurrencyTests.swift b/Tests/VergeTests/ConcurrencyTests.swift
index 879b594936..fe84fa690f 100644
--- a/Tests/VergeTests/ConcurrencyTests.swift
+++ b/Tests/VergeTests/ConcurrencyTests.swift
@@ -74,17 +74,18 @@ final class ConcurrencyTests: XCTestCase {
     let store1 = DemoStore()
 
     let exp = expectation(description: "11")
-    let count = OSAllocatedUnfairLock<Int>.init(initialState: 0)
+
+    let count = VergeConcurrency.UnfairLockAtomic<Int>.init(0)
 
     DispatchQueue.global().async {
       let cancellable = store1.sinkState(queue: .startsFromCurrentThread(andUse: .mainIsolated())) {
         state in
 
         defer {
-          count.withLock { $0 += 1 }
+          count.modify { $0 += 1 }
         }
 
-        if count.withLock({ $0 == 0 }) {
+        if count.modify({ $0 == 0 }) {
           XCTAssertEqual(Thread.isMainThread, false)
         } else {
           XCTAssertEqual(Thread.isMainThread, true)
@@ -109,12 +110,12 @@ final class ConcurrencyTests: XCTestCase {
 
     for i in 0..<100 {
       do {
-        let version = OSAllocatedUnfairLock<UInt64>.init(initialState: 0)
+        let version = VergeConcurrency.UnfairLockAtomic<UInt64>.init(0)
         store.sinkState(queue: .passthrough) { s in
-          if version.withLock({ $0 > s.version }) {
+          if version.modify({ $0 > s.version }) {
             XCTFail()
           }
-          version.withLock { $0 = s.version }
+          version.modify { $0 = s.version }
           print("\(i)", s.version)
         }
         .store(in: &bag)
@@ -122,12 +123,12 @@ final class ConcurrencyTests: XCTestCase {
     }
 
     do {
-      let version = OSAllocatedUnfairLock<UInt64>.init(initialState: 0)
+      let version = VergeConcurrency.UnfairLockAtomic<UInt64>.init(0)
       store.sinkState(queue: .passthrough) { s in
-        if version.withLock({ $0 > s.version }) {
+        if version.modify({ $0 > s.version }) {
           XCTFail()
         }
-        version.withLock { $0 = s.version }
+        version.modify { $0 = s.version }
         print("x", s.version)
         store.commit {
           if s.count == 1 {
diff --git a/Tests/VergeTests/PipelineTests.swift b/Tests/VergeTests/PipelineTests.swift
index ab3cd4b936..875cc0ce6b 100644
--- a/Tests/VergeTests/PipelineTests.swift
+++ b/Tests/VergeTests/PipelineTests.swift
@@ -1,20 +1,21 @@
 
 import XCTest
 import Verge
-import os.lock
 
 final class PipelineTests: XCTestCase {
   
   func test_MapPipeline() {
-    
-    let mapCounter = OSAllocatedUnfairLock<Int>.init(initialState: 0)
+        
+    let mapCounter = VergeConcurrency.UnfairLockAtomic<Int>.init(0)
     
     let pipeline = Pipelines.ChangesMapPipeline<DemoState, _, _>(
       intermediate: {
         $0
       },
       transform: {
-        mapCounter.withLock { $0 += 1 }
+        mapCounter.modify { 
+          $0 += 1
+        }
         return $0.name.count
       },
       additionalDropCondition: nil
@@ -33,7 +34,7 @@ final class PipelineTests: XCTestCase {
         .noUpdates
       )
       
-      XCTAssertEqual(mapCounter.withLock { $0 }, 0)
+      XCTAssertEqual(mapCounter.value, 0)
     }
     
     do {
@@ -48,7 +49,7 @@ final class PipelineTests: XCTestCase {
         .noUpdates
       )
       
-      XCTAssertEqual(mapCounter.withLock { $0 }, 2)
+      XCTAssertEqual(mapCounter.value , 2)
       
     }
     
@@ -56,14 +57,14 @@ final class PipelineTests: XCTestCase {
  
   func test_MapPipeline_Intermediate() {
     
-    let mapCounter = OSAllocatedUnfairLock<Int>.init(initialState: 0)    
+    let mapCounter = VergeConcurrency.UnfairLockAtomic<Int>.init(0)
     
     let pipeline = Pipelines.ChangesMapPipeline<DemoState, _, _>(
       intermediate: {
         $0.name
       },
       transform: {
-        mapCounter.withLock { $0 += 1 }
+        mapCounter.modify { $0 += 1 }
         return $0.count
       },
       additionalDropCondition: nil
@@ -82,7 +83,7 @@ final class PipelineTests: XCTestCase {
         .noUpdates
       )
       
-      XCTAssertEqual(mapCounter.withLock { $0 }, 0)
+      XCTAssertEqual(mapCounter.value, 0)
     }
     
     do {
@@ -97,7 +98,7 @@ final class PipelineTests: XCTestCase {
         .noUpdates
       )
       
-      XCTAssertEqual(mapCounter.withLock { $0 }, 0)
+      XCTAssertEqual(mapCounter.value, 0)
       
     }
         
diff --git a/Tests/VergeTests/VergeStoreTests.swift b/Tests/VergeTests/VergeStoreTests.swift
index 2375981782..256b8dab50 100644
--- a/Tests/VergeTests/VergeStoreTests.swift
+++ b/Tests/VergeTests/VergeStoreTests.swift
@@ -216,10 +216,10 @@ final class VergeStoreTests: XCTestCase {
 
     let store = DemoStore()
 
-    let count = OSAllocatedUnfairLock<Int>.init(initialState: 0)
+    let count = VergeConcurrency.UnfairLockAtomic<Int>.init(0)
 
     let subs = store.sinkState(queue: .passthrough) { (_) in
-      count.withLock { $0 += 1 }
+      count.modify { $0 += 1 }
     }
 
     XCTAssertEqual(store.state.version, 0)
@@ -256,7 +256,7 @@ final class VergeStoreTests: XCTestCase {
     }
 
     XCTAssertEqual(store.state.version, 2)
-    XCTAssertEqual(count.withLock { $0 }, 3)
+    XCTAssertEqual(count.value, 3)
 
     withExtendedLifetime(subs, {})
     
@@ -308,10 +308,10 @@ final class VergeStoreTests: XCTestCase {
   func testSubscription() {
     
     var subscriptions = Set<AnyCancellable>()
-    let count = OSAllocatedUnfairLock<Int>.init(initialState: 0)
+    let count = VergeConcurrency.UnfairLockAtomic<Int>.init(0)
     
     store.sinkState(queue: .passthrough) { (changes) in
-      count.withLock {
+      count.modify {
         $0 += 1
       }
     }
@@ -328,7 +328,7 @@ final class VergeStoreTests: XCTestCase {
       $0.markAsModified()
     }
     
-    XCTAssertEqual(count.withLock { $0 }, 2)
+    XCTAssertEqual(count.value, 2)
     
   }