diff --git a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClient+execute.swift b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClient+execute.swift
index 3c0566c9e..6c45a590b 100644
--- a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClient+execute.swift
+++ b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClient+execute.swift
@@ -12,13 +12,13 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import struct Foundation.URL
 import Logging
 import NIOCore
 import NIOHTTP1
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClient {
     /// Execute arbitrary HTTP requests.
     ///
@@ -41,7 +41,7 @@ extension HTTPClient {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClient {
     private func executeAndFollowRedirectsIfNeeded(
         _ request: HTTPClientRequest,
@@ -124,7 +124,7 @@ extension HTTPClient {
 /// There is currently no good way to asynchronously cancel an object that is initiated inside the `body` closure of `with*Continuation`.
 /// As a workaround we use `TransactionCancelHandler` which will take care of the race between instantiation of `Transaction`
 /// in the `body` closure and cancelation from the `onCancel` closure  of `withTaskCancellationHandler`.
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 private actor TransactionCancelHandler {
     enum CancelReason {
         /// swift concurrency task was canceled
diff --git a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest+Prepared.swift b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest+Prepared.swift
index 974616143..7899588e1 100644
--- a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest+Prepared.swift
+++ b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest+Prepared.swift
@@ -12,11 +12,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import struct Foundation.URL
 import NIOHTTP1
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientRequest {
     struct Prepared {
         var url: URL
@@ -27,7 +27,7 @@ extension HTTPClientRequest {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientRequest.Prepared {
     init(_ request: HTTPClientRequest) throws {
         guard let url = URL(string: request.url) else {
@@ -58,7 +58,7 @@ extension HTTPClientRequest.Prepared {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension RequestBodyLength {
     init(_ body: HTTPClientRequest.Body?) {
         switch body?.mode {
@@ -74,7 +74,7 @@ extension RequestBodyLength {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientRequest.Prepared {
     func followingRedirect(to redirectURL: URL, status: HTTPResponseStatus) -> HTTPClientRequest {
         let (method, headers, body) = transformRequestForRedirect(
diff --git a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest.swift b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest.swift
index 3c729b75c..89689225d 100644
--- a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest.swift
+++ b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientRequest.swift
@@ -12,11 +12,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import NIOCore
 import NIOHTTP1
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 struct HTTPClientRequest {
     var url: String
     var method: HTTPMethod
@@ -32,7 +32,7 @@ struct HTTPClientRequest {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientRequest {
     struct Body {
         internal enum Mode {
@@ -49,7 +49,7 @@ extension HTTPClientRequest {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientRequest.Body {
     static func byteBuffer(_ byteBuffer: ByteBuffer) -> Self {
         self.init(.byteBuffer(byteBuffer))
@@ -131,7 +131,7 @@ extension HTTPClientRequest.Body {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Optional where Wrapped == HTTPClientRequest.Body {
     internal var canBeConsumedMultipleTimes: Bool {
         switch self?.mode {
diff --git a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientResponse.swift b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientResponse.swift
index 2df1b808c..1ecfed9e5 100644
--- a/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientResponse.swift
+++ b/Sources/AsyncHTTPClient/AsyncAwait/HTTPClientResponse.swift
@@ -12,11 +12,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import NIOCore
 import NIOHTTP1
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 struct HTTPClientResponse {
     var version: HTTPVersion
     var status: HTTPResponseStatus
@@ -46,7 +46,7 @@ struct HTTPClientResponse {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientResponse.Body: AsyncSequence {
     typealias Element = ByteBuffer
     typealias AsyncIterator = Iterator
@@ -70,7 +70,7 @@ extension HTTPClientResponse.Body: AsyncSequence {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientResponse.Body {
     /// The purpose of this object is to inform the transaction about the response body being deinitialized.
     /// If the users has not called `makeAsyncIterator` on the body, before it is deinited, the http
@@ -88,7 +88,7 @@ extension HTTPClientResponse.Body {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension HTTPClientResponse.Body {
     internal class IteratorStream {
         struct ID: Hashable {
diff --git a/Sources/AsyncHTTPClient/AsyncAwait/Transaction+StateMachine.swift b/Sources/AsyncHTTPClient/AsyncAwait/Transaction+StateMachine.swift
index 98fce4aed..dea1093db 100644
--- a/Sources/AsyncHTTPClient/AsyncAwait/Transaction+StateMachine.swift
+++ b/Sources/AsyncHTTPClient/AsyncAwait/Transaction+StateMachine.swift
@@ -11,12 +11,12 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 //===----------------------------------------------------------------------===//
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import Logging
 import NIOCore
 import NIOHTTP1
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction {
     struct StateMachine {
         struct ExecutionContext {
diff --git a/Sources/AsyncHTTPClient/AsyncAwait/Transaction.swift b/Sources/AsyncHTTPClient/AsyncAwait/Transaction.swift
index f7a3ab03d..c2ce52eeb 100644
--- a/Sources/AsyncHTTPClient/AsyncAwait/Transaction.swift
+++ b/Sources/AsyncHTTPClient/AsyncAwait/Transaction.swift
@@ -12,14 +12,14 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import Logging
 import NIOConcurrencyHelpers
 import NIOCore
 import NIOHTTP1
 import NIOSSL
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 final class Transaction: @unchecked Sendable {
     let logger: Logger
 
@@ -145,7 +145,7 @@ final class Transaction: @unchecked Sendable {
 
 // MARK: - Protocol Methods -
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction: HTTPSchedulableRequest {
     var poolKey: ConnectionPool.Key { self.request.poolKey }
     var tlsConfiguration: TLSConfiguration? { return nil }
@@ -158,7 +158,7 @@ extension Transaction: HTTPSchedulableRequest {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction: HTTPExecutableRequest {
     var requestHead: HTTPRequestHead { self.request.head }
 
@@ -316,7 +316,7 @@ extension Transaction: HTTPExecutableRequest {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction {
     func responseBodyDeinited() {
         let deinitedAction = self.stateLock.withLock {
diff --git a/Tests/AsyncHTTPClientTests/AsyncAwaitEndToEndTests.swift b/Tests/AsyncHTTPClientTests/AsyncAwaitEndToEndTests.swift
index 7c5f61681..314695e97 100644
--- a/Tests/AsyncHTTPClientTests/AsyncAwaitEndToEndTests.swift
+++ b/Tests/AsyncHTTPClientTests/AsyncAwaitEndToEndTests.swift
@@ -34,8 +34,8 @@ private func makeDefaultHTTPClient(
 
 final class AsyncAwaitEndToEndTests: XCTestCase {
     func testSimpleGet() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false))
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -57,8 +57,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testSimplePost() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false))
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -80,8 +80,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithByteBuffer() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -105,8 +105,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithSequenceOfUInt8() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -130,8 +130,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithCollectionOfUInt8() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -155,8 +155,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithRandomAccessCollectionOfUInt8() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -180,8 +180,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithAsyncSequenceOfByteBuffers() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -209,8 +209,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithAsyncSequenceOfUInt8() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -234,8 +234,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithFragmentedAsyncSequenceOfByteBuffers() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -276,8 +276,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testPostWithFragmentedAsyncSequenceOfLargeByteBuffers() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let bin = HTTPBin(.http2(compress: false)) { _ in HTTPEchoHandler() }
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -319,8 +319,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testCanceling() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest(timeout: 5) {
             let bin = HTTPBin(.http2(compress: false))
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -344,8 +344,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testDeadline() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest(timeout: 5) {
             let bin = HTTPBin(.http2(compress: false))
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -365,8 +365,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testImmediateDeadline() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest(timeout: 5) {
             let bin = HTTPBin(.http2(compress: false))
             defer { XCTAssertNoThrow(try bin.shutdown()) }
@@ -386,8 +386,8 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 
     func testInvalidURL() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest(timeout: 5) {
             let client = makeDefaultHTTPClient()
             defer { XCTAssertNoThrow(try client.syncShutdown()) }
@@ -402,7 +402,7 @@ final class AsyncAwaitEndToEndTests: XCTestCase {
     }
 }
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 extension AsyncSequence where Element == ByteBuffer {
     func collect() async rethrows -> ByteBuffer {
         try await self.reduce(into: ByteBuffer()) { accumulatingBuffer, nextBuffer in
diff --git a/Tests/AsyncHTTPClientTests/AsyncTestHelpers.swift b/Tests/AsyncHTTPClientTests/AsyncTestHelpers.swift
index 36813091f..312008959 100644
--- a/Tests/AsyncHTTPClientTests/AsyncTestHelpers.swift
+++ b/Tests/AsyncHTTPClientTests/AsyncTestHelpers.swift
@@ -12,11 +12,11 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if swift(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import NIOConcurrencyHelpers
 import NIOCore
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 class AsyncSequenceWriter<Element>: AsyncSequence {
     typealias AsyncIterator = Iterator
 
diff --git a/Tests/AsyncHTTPClientTests/HTTPClientRequestTests.swift b/Tests/AsyncHTTPClientTests/HTTPClientRequestTests.swift
index 082f37761..f47b0ef93 100644
--- a/Tests/AsyncHTTPClientTests/HTTPClientRequestTests.swift
+++ b/Tests/AsyncHTTPClientTests/HTTPClientRequestTests.swift
@@ -17,17 +17,17 @@ import NIOCore
 import XCTest
 
 class HTTPClientRequestTests: XCTestCase {
-    #if compiler(>=5.5) && canImport(_Concurrency)
-    @available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+    #if compiler(>=5.5.2) && canImport(_Concurrency)
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
     private typealias Request = HTTPClientRequest
 
-    @available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
     private typealias PreparedRequest = HTTPClientRequest.Prepared
     #endif
 
     func testCustomHeadersAreRespected() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "https://example.com/get")
             request.headers = [
@@ -62,8 +62,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testUnixScheme() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "unix://%2Fexample%2Ffolder.sock/some_path")
             request.headers = ["custom-header": "custom-value"]
@@ -93,8 +93,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testHTTPUnixScheme() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http+unix://%2Fexample%2Ffolder.sock/some_path")
             request.headers = ["custom-header": "custom-value"]
@@ -124,8 +124,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testHTTPSUnixScheme() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "https+unix://%2Fexample%2Ffolder.sock/some_path")
             request.headers = ["custom-header": "custom-value"]
@@ -155,8 +155,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testGetWithoutBody() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let request = Request(url: "https://example.com/get")
             var preparedRequest: PreparedRequest?
@@ -185,8 +185,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithoutBody() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -220,8 +220,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithEmptyByteBuffer() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -256,8 +256,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithByteBuffer() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -291,8 +291,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithSequenceOfUnknownLength() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -327,8 +327,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithSequenceWithFixedLength() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -364,8 +364,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithRandomAccessCollection() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -400,8 +400,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithAsyncSequenceOfUnknownLength() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -441,8 +441,8 @@ class HTTPClientRequestTests: XCTestCase {
     }
 
     func testPostWithAsyncSequenceWithKnownLength() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             var request = Request(url: "http://example.com/post")
             request.method = .POST
@@ -482,13 +482,13 @@ class HTTPClientRequestTests: XCTestCase {
     }
 }
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 private struct LengthMismatch: Error {
     var announcedLength: Int
     var actualLength: Int
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Optional where Wrapped == HTTPClientRequest.Body {
     /// Accumulates all data from `self` into a single `ByteBuffer` and checks that the user specified length matches
     /// the length of the accumulated data.
@@ -549,7 +549,7 @@ extension Collection {
     }
 }
 
-@available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 struct AsyncSequenceFromSyncSequence<Wrapped: Sequence>: AsyncSequence {
     typealias Element = Wrapped.Element
     struct AsyncIterator: AsyncIteratorProtocol {
@@ -566,7 +566,7 @@ struct AsyncSequenceFromSyncSequence<Wrapped: Sequence>: AsyncSequence {
     }
 }
 
-@available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Sequence {
     /// Turns `self` into an `AsyncSequence` by wending each element of `self` asynchronously.
     func asAsyncSequence() -> AsyncSequenceFromSyncSequence<Self> {
diff --git a/Tests/AsyncHTTPClientTests/Transaction+StateMachineTests.swift b/Tests/AsyncHTTPClientTests/Transaction+StateMachineTests.swift
index 3237d19e8..ff1972330 100644
--- a/Tests/AsyncHTTPClientTests/Transaction+StateMachineTests.swift
+++ b/Tests/AsyncHTTPClientTests/Transaction+StateMachineTests.swift
@@ -20,8 +20,8 @@ import XCTest
 
 final class Transaction_StateMachineTests: XCTestCase {
     func testRequestWasQueuedAfterWillExecuteRequestWasCalled() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         let eventLoop = EmbeddedEventLoop()
         XCTAsyncTest {
             func workaround(_ continuation: CheckedContinuation<HTTPClientResponse, Error>) {
@@ -50,8 +50,8 @@ final class Transaction_StateMachineTests: XCTestCase {
     }
 
     func testRequestBodyStreamWasPaused() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         let eventLoop = EmbeddedEventLoop()
         XCTAsyncTest {
             func workaround(_ continuation: CheckedContinuation<HTTPClientResponse, Error>) {
@@ -73,8 +73,8 @@ final class Transaction_StateMachineTests: XCTestCase {
     }
 
     func testQueuedRequestGetsRemovedWhenDeadlineExceeded() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             func workaround(_ continuation: CheckedContinuation<HTTPClientResponse, Error>) {
                 var state = Transaction.StateMachine(continuation)
@@ -97,8 +97,8 @@ final class Transaction_StateMachineTests: XCTestCase {
     }
 
     func testScheduledRequestGetsRemovedWhenDeadlineExceeded() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         let eventLoop = EmbeddedEventLoop()
         XCTAsyncTest {
             func workaround(_ continuation: CheckedContinuation<HTTPClientResponse, Error>) {
@@ -124,8 +124,8 @@ final class Transaction_StateMachineTests: XCTestCase {
     }
 
     func testRequestWithHeadReceivedGetNotCancelledWhenDeadlineExceeded() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         let eventLoop = EmbeddedEventLoop()
         XCTAsyncTest {
             func workaround(_ continuation: CheckedContinuation<HTTPClientResponse, Error>) {
@@ -154,8 +154,8 @@ final class Transaction_StateMachineTests: XCTestCase {
     }
 }
 
-#if compiler(>=5.5) && canImport(_Concurrency)
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction.StateMachine.StartExecutionAction: Equatable {
     public static func == (lhs: Self, rhs: Self) -> Bool {
         switch (lhs, rhs) {
@@ -172,7 +172,7 @@ extension Transaction.StateMachine.StartExecutionAction: Equatable {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction.StateMachine.ResumeProducingAction: Equatable {
     public static func == (lhs: Self, rhs: Self) -> Bool {
         switch (lhs, rhs) {
@@ -188,7 +188,7 @@ extension Transaction.StateMachine.ResumeProducingAction: Equatable {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction.StateMachine.NextWriteAction: Equatable {
     public static func == (lhs: Self, rhs: Self) -> Bool {
         switch (lhs, rhs) {
diff --git a/Tests/AsyncHTTPClientTests/TransactionTests.swift b/Tests/AsyncHTTPClientTests/TransactionTests.swift
index 9513605f7..8857253b6 100644
--- a/Tests/AsyncHTTPClientTests/TransactionTests.swift
+++ b/Tests/AsyncHTTPClientTests/TransactionTests.swift
@@ -21,15 +21,15 @@ import NIOHTTP1
 import NIOPosix
 import XCTest
 
-#if compiler(>=5.5) && canImport(_Concurrency)
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 typealias PreparedRequest = HTTPClientRequest.Prepared
 #endif
 
 final class TransactionTests: XCTestCase {
     func testCancelAsyncRequest() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -64,8 +64,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testResponseStreamingWorks() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -127,8 +127,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testIgnoringResponseBodyWorks() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -178,8 +178,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testWriteBackpressureWorks() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -252,8 +252,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testSimpleGetRequest() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
             let eventLoop = eventLoopGroup.next()
@@ -310,8 +310,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testSimplePostRequest() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -350,8 +350,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testPostStreamFails() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -395,8 +395,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testResponseStreamFails() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let embeddedEventLoop = EmbeddedEventLoop()
             defer { XCTAssertNoThrow(try embeddedEventLoop.syncShutdownGracefully()) }
@@ -458,8 +458,8 @@ final class TransactionTests: XCTestCase {
     }
 
     func testBiDirectionalStreamingHTTP2() {
-        #if compiler(>=5.5) && canImport(_Concurrency)
-        guard #available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *) else { return }
+        #if compiler(>=5.5.2) && canImport(_Concurrency)
+        guard #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) else { return }
         XCTAsyncTest {
             let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
             let eventLoop = eventLoopGroup.next()
@@ -533,12 +533,12 @@ final class TransactionTests: XCTestCase {
     }
 }
 
-#if compiler(>=5.5) && canImport(_Concurrency)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 
 // This needs a small explanation. If an iterator is a struct, it can't be used across multiple
 // tasks. Since we want to wait for things to happen in tests, we need to `async let`, which creates
 // implicit tasks. Therefore we need to wrap our iterator struct.
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 actor SharedIterator<Iterator: AsyncIteratorProtocol> {
     private var iterator: Iterator
 
@@ -553,7 +553,7 @@ actor SharedIterator<Iterator: AsyncIteratorProtocol> {
     }
 }
 
-@available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 extension Transaction {
     fileprivate static func makeWithResultTask(
         request: PreparedRequest,
diff --git a/Tests/AsyncHTTPClientTests/XCTest+AsyncAwait.swift b/Tests/AsyncHTTPClientTests/XCTest+AsyncAwait.swift
index f26e11582..fbc429b10 100644
--- a/Tests/AsyncHTTPClientTests/XCTest+AsyncAwait.swift
+++ b/Tests/AsyncHTTPClientTests/XCTest+AsyncAwait.swift
@@ -26,11 +26,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#if compiler(>=5.5)
+#if compiler(>=5.5.2) && canImport(_Concurrency)
 import XCTest
 
 extension XCTestCase {
-    @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
+    @available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
     /// Cross-platform XCTest support for async-await tests.
     ///
     /// Currently the Linux implementation of XCTest doesn't have async-await support.
@@ -61,7 +61,7 @@ extension XCTestCase {
     }
 }
 
-@available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 internal func XCTAssertThrowsError<T>(
     _ expression: @autoclosure () async throws -> T,
     verify: (Error) -> Void = { _ in },
@@ -76,7 +76,7 @@ internal func XCTAssertThrowsError<T>(
     }
 }
 
-@available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
+@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
 internal func XCTAssertNoThrowWithResult<Result>(
     _ expression: @autoclosure () async throws -> Result,
     file: StaticString = #file,
@@ -90,4 +90,4 @@ internal func XCTAssertNoThrowWithResult<Result>(
     return nil
 }
 
-#endif // compiler(>=5.5)
+#endif