diff --git a/Package.swift b/Package.swift
index 3309ad3..a341786 100644
--- a/Package.swift
+++ b/Package.swift
@@ -12,9 +12,9 @@ import PackageDescription
 
 
 #if swift(<6)
-let swiftConcurrency: SwiftSetting = .enableExperimentalFeature("SwiftConcurrency")
+let swiftConcurrency: SwiftSetting = .enableExperimentalFeature("StrictConcurrency")
 #else
-let swiftConcurrency: SwiftSetting = .enableUpcomingFeature("SwiftConcurrency")
+let swiftConcurrency: SwiftSetting = .enableUpcomingFeature("StrictConcurrency")
 #endif
 
 
diff --git a/Sources/XCTestApp/TestAppTestCase.swift b/Sources/XCTestApp/TestAppTestCase.swift
index 37a7802..943ff3d 100644
--- a/Sources/XCTestApp/TestAppTestCase.swift
+++ b/Sources/XCTestApp/TestAppTestCase.swift
@@ -10,6 +10,7 @@
 /// A collection of test cases that can be executed in an ``TestAppView``.
 public protocol TestAppTestCase: Identifiable {
     /// Implement this method to run all the tests that should be executed.
+    @MainActor
     func runTests() async throws
 }
 
diff --git a/Sources/XCTestExtensions/XCTAssertThrowsErrorAsync.swift b/Sources/XCTestExtensions/XCTAssertThrowsErrorAsync.swift
index c93cbb7..21a96a6 100644
--- a/Sources/XCTestExtensions/XCTAssertThrowsErrorAsync.swift
+++ b/Sources/XCTestExtensions/XCTAssertThrowsErrorAsync.swift
@@ -20,11 +20,11 @@ import XCTest
 ///   - line: The line number where the failure occurs. The default is the line number where you call this function.
 ///   - errorHandler: An optional handler for errors that expression throws.
 public func XCTAssertThrowsErrorAsync<T>(
-    _ expression: @autoclosure () async throws -> T,
-    _ message: @autoclosure () -> String = "",
+    _ expression: @autoclosure @Sendable  () async throws -> T,
+    _ message: @autoclosure @Sendable () -> String = "",
     file: StaticString = #filePath,
     line: UInt = #line,
-    _ errorHandler: (Error) throws -> Void = { _ in }
+    _ errorHandler: @Sendable (Error) throws -> Void = { _ in }
 ) async rethrows {
     do {
         _ = try await expression()
diff --git a/Sources/XCTestExtensions/XCTestCase+DisablePasswordAutofill.swift b/Sources/XCTestExtensions/XCTestCase+DisablePasswordAutofill.swift
index 2b23e4f..c748552 100644
--- a/Sources/XCTestExtensions/XCTestCase+DisablePasswordAutofill.swift
+++ b/Sources/XCTestExtensions/XCTestCase+DisablePasswordAutofill.swift
@@ -33,6 +33,7 @@ extension XCTestCase {
     @available(macOS, unavailable)
     @available(tvOS, unavailable)
     @available(visionOS, unavailable)
+    @MainActor
     public func disablePasswordAutofill() throws {
         let settingsApp = XCUIApplication(bundleIdentifier: "com.apple.Preferences")
         settingsApp.terminate()
diff --git a/Sources/XCTestExtensions/XCUIElement+TextEntry.swift b/Sources/XCTestExtensions/XCUIElement+TextEntry.swift
index 1a6501c..1a515fd 100644
--- a/Sources/XCTestExtensions/XCUIElement+TextEntry.swift
+++ b/Sources/XCTestExtensions/XCUIElement+TextEntry.swift
@@ -13,7 +13,7 @@ import XCTest
 /// An internal flag that is used to test the flaky simulator text entry behavior in the iOS simulator.
 ///
 /// Do not use this flag outside of the UI tests in the ``XCTestExtensions`` target!
-var simulateFlakySimulatorTextEntry = false
+@MainActor var simulateFlakySimulatorTextEntry = false
 
 
 extension XCUIElement {
diff --git a/Tests/UITests/TestAppUITests/XCTestExtensionsTests.swift b/Tests/UITests/TestAppUITests/XCTestExtensionsTests.swift
index 8862b43..47e5dbb 100644
--- a/Tests/UITests/TestAppUITests/XCTestExtensionsTests.swift
+++ b/Tests/UITests/TestAppUITests/XCTestExtensionsTests.swift
@@ -59,6 +59,7 @@ class XCTestExtensionsTests: XCTestCase {
         XCTAssert(app.staticTexts["No secure text set ..."].waitForExistence(timeout: 5))
     }
     
+    @MainActor
     func testDisablePasswordAutofill() throws {
         #if os(iOS)
         try disablePasswordAutofill()
@@ -75,6 +76,7 @@ class XCTestExtensionsTests: XCTestCase {
         try app.callTextEntryExtensions()
     }
     
+    @MainActor
     func testFlakyTextEntry() throws {
         let app = XCUIApplication()
         app.launch()