diff --git a/Sources/OpenAPIURLSession/URLSessionTransport.swift b/Sources/OpenAPIURLSession/URLSessionTransport.swift
index d3780dc..7f73ab4 100644
--- a/Sources/OpenAPIURLSession/URLSessionTransport.swift
+++ b/Sources/OpenAPIURLSession/URLSessionTransport.swift
@@ -12,9 +12,19 @@
 //
 //===----------------------------------------------------------------------===//
 import OpenAPIRuntime
+#if canImport(Darwin)
 import Foundation
+#else
+@preconcurrency import struct Foundation.URL
+@preconcurrency import struct Foundation.URLComponents
+@preconcurrency import struct Foundation.Data
+@preconcurrency import protocol Foundation.LocalizedError
+#endif
 #if canImport(FoundationNetworking)
-@preconcurrency import FoundationNetworking
+@preconcurrency import struct FoundationNetworking.URLRequest
+@preconcurrency import class FoundationNetworking.URLSession
+@preconcurrency import class FoundationNetworking.URLResponse
+@preconcurrency import class FoundationNetworking.HTTPURLResponse
 #endif
 
 /// A client transport that performs HTTP operations using the URLSession type
diff --git a/Tests/OpenAPIURLSessionTests/Locking.swift b/Tests/OpenAPIURLSessionTests/Locking.swift
new file mode 100644
index 0000000..1d86fe4
--- /dev/null
+++ b/Tests/OpenAPIURLSessionTests/Locking.swift
@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftOpenAPIGenerator open source project
+//
+// Copyright (c) 2023 Apple Inc. and the SwiftOpenAPIGenerator project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftOpenAPIGenerator project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+/// A wrapper providing locked access to a value.
+///
+/// Marked as @unchecked Sendable due to the synchronization being
+/// performed manually using locks.
+///
+/// Note: Use the `package` access modifier once min Swift version is increased.
+@_spi(Locking)
+public final class LockedValueBox<Value: Sendable>: @unchecked Sendable {
+    private let lock: NSLock = {
+        let lock = NSLock()
+        lock.name = "com.apple.swift-openapi-urlsession.lock.LockedValueBox"
+        return lock
+    }()
+    private var value: Value
+    public init(_ value: Value) {
+        self.value = value
+    }
+    public func withValue<R>(_ work: (inout Value) throws -> R) rethrows -> R {
+        lock.lock()
+        defer {
+            lock.unlock()
+        }
+        return try work(&value)
+    }
+}
diff --git a/Tests/OpenAPIURLSessionTests/URLSessionTransportTests.swift b/Tests/OpenAPIURLSessionTests/URLSessionTransportTests.swift
index 9baec4a..6e9d02b 100644
--- a/Tests/OpenAPIURLSessionTests/URLSessionTransportTests.swift
+++ b/Tests/OpenAPIURLSessionTests/URLSessionTransportTests.swift
@@ -13,9 +13,18 @@
 //===----------------------------------------------------------------------===//
 import XCTest
 import OpenAPIRuntime
+#if canImport(Darwin)
 import Foundation
+#else
+@preconcurrency import struct Foundation.URL
+#endif
 #if canImport(FoundationNetworking)
-import FoundationNetworking
+@preconcurrency import struct FoundationNetworking.URLRequest
+@preconcurrency import class FoundationNetworking.URLProtocol
+@preconcurrency import class FoundationNetworking.URLSession
+@preconcurrency import class FoundationNetworking.HTTPURLResponse
+@preconcurrency import class FoundationNetworking.URLResponse
+@preconcurrency import class FoundationNetworking.URLSessionConfiguration
 #endif
 @testable import OpenAPIURLSession
 
@@ -53,12 +62,14 @@ class URLSessionTransportTests: XCTestCase {
 
     func testSend() async throws {
         let endpointURL = URL(string: "http://example.com/api/hello/Maria?greeting=Howdy")!
-        MockURLProtocol.mockHTTPResponses[endpointURL] = .success(
-            (
-                HTTPURLResponse(url: endpointURL, statusCode: 201, httpVersion: nil, headerFields: [:])!,
-                body: Data("👋".utf8)
+        MockURLProtocol.mockHTTPResponses.withValue { map in
+            map[endpointURL] = .success(
+                (
+                    HTTPURLResponse(url: endpointURL, statusCode: 201, httpVersion: nil, headerFields: [:])!,
+                    body: Data("👋".utf8)
+                )
             )
-        )
+        }
         let transport: any ClientTransport = URLSessionTransport(
             configuration: .init(session: MockURLProtocol.mockURLSession)
         )
@@ -81,9 +92,10 @@ class URLSessionTransportTests: XCTestCase {
 }
 
 class MockURLProtocol: URLProtocol {
-    static var mockHTTPResponses: [URL: Result<(response: HTTPURLResponse, body: Data?), any Error>] = [:]
+    typealias MockHTTPResponseMap = [URL: Result<(response: HTTPURLResponse, body: Data?), any Error>]
+    static let mockHTTPResponses = LockedValueBox<MockHTTPResponseMap>([:])
 
-    static var recordedHTTPRequests: [URLRequest] = []
+    static let recordedHTTPRequests = LockedValueBox<[URLRequest]>([])
 
     override class func canInit(with request: URLRequest) -> Bool { true }
 
@@ -92,9 +104,11 @@ class MockURLProtocol: URLProtocol {
     override func stopLoading() {}
 
     override func startLoading() {
-        Self.recordedHTTPRequests.append(self.request)
+        Self.recordedHTTPRequests.withValue { $0.append(self.request) }
         guard let url = self.request.url else { return }
-        guard let response = Self.mockHTTPResponses[url] else { return }
+        guard let response = Self.mockHTTPResponses.withValue({ $0[url] }) else {
+            return
+        }
         switch response {
         case .success(let mockResponse):
             client?.urlProtocol(self, didReceive: mockResponse.response, cacheStoragePolicy: .notAllowed)
diff --git a/docker/docker-compose.2204.58.yaml b/docker/docker-compose.2204.58.yaml
index 738fed2..987f3d2 100644
--- a/docker/docker-compose.2204.58.yaml
+++ b/docker/docker-compose.2204.58.yaml
@@ -13,6 +13,7 @@ services:
     environment:
       - WARN_AS_ERROR_ARG=-Xswiftc -warnings-as-errors
       - IMPORT_CHECK_ARG=--explicit-target-dependency-import-check error
+      - STRICT_CONCURRENCY_ARG=-Xswiftc -strict-concurrency=complete
 
   shell:
     image: *image
diff --git a/docker/docker-compose.2204.59.yaml b/docker/docker-compose.2204.59.yaml
index ec87e09..47a3c43 100644
--- a/docker/docker-compose.2204.59.yaml
+++ b/docker/docker-compose.2204.59.yaml
@@ -12,6 +12,7 @@ services:
     environment:
       - WARN_AS_ERROR_ARG=-Xswiftc -warnings-as-errors
       - IMPORT_CHECK_ARG=--explicit-target-dependency-import-check error
+      - STRICT_CONCURRENCY_ARG=-Xswiftc -strict-concurrency=complete
 
   shell:
     image: *image
diff --git a/docker/docker-compose.2204.main.yaml b/docker/docker-compose.2204.main.yaml
index d182bf4..ef0e43e 100644
--- a/docker/docker-compose.2204.main.yaml
+++ b/docker/docker-compose.2204.main.yaml
@@ -13,6 +13,7 @@ services:
     environment:
       - WARN_AS_ERROR_ARG=-Xswiftc -warnings-as-errors
       - IMPORT_CHECK_ARG=--explicit-target-dependency-import-check error
+      - STRICT_CONCURRENCY_ARG=-Xswiftc -strict-concurrency=complete
 
   shell:
     image: *image
diff --git a/docker/docker-compose.yaml b/docker/docker-compose.yaml
index 41ed6e1..d1ea158 100644
--- a/docker/docker-compose.yaml
+++ b/docker/docker-compose.yaml
@@ -30,7 +30,7 @@ services:
 
   test:
     <<: *common
-    command: /bin/bash -xcl "swift $${SWIFT_TEST_VERB-test} $${WARN_AS_ERROR_ARG-} $${SANITIZER_ARG-} $${IMPORT_CHECK_ARG-}"
+    command: /bin/bash -xcl "swift $${SWIFT_TEST_VERB-test} $${WARN_AS_ERROR_ARG-} $${SANITIZER_ARG-} $${IMPORT_CHECK_ARG-} $${STRICT_CONCURRENCY_ARG-}"
 
   shell:
     <<: *common