diff --git a/.github/workflows/sessions.yml b/.github/workflows/sessions.yml
index f5372a2091b..055f604457b 100644
--- a/.github/workflows/sessions.yml
+++ b/.github/workflows/sessions.yml
@@ -39,10 +39,17 @@ jobs:
           - os: macos-14
             xcode: Xcode_16.2
             tests:
+            swift_version: 5.9
           # Flaky tests on CI
           - os: macos-15
             xcode: Xcode_16.3
             tests: --skip-tests
+            swift_version: 5.9
+          # Flaky tests on CI
+          - os: macos-15
+            xcode: Xcode_16.2
+            tests: --skip-tests
+            swift_version: 6.0
     runs-on: ${{ matrix.build-env.os }}
     steps:
     - uses: actions/checkout@v4
@@ -51,6 +58,8 @@ jobs:
       run: scripts/setup_bundler.sh
     - name: Xcode
       run: sudo xcode-select -s /Applications/${{ matrix.build-env.xcode }}.app/Contents/Developer
+    - name: Set Swift swift_version
+      run: sed -i "" "s/s.swift_version[[:space:]]*=[[:space:]]*'5.9'/s.swift_version = '${{ matrix.build-env.swift_version }}'/" FirebaseSessions.podspec
     - uses: nick-fields/retry@ce71cc2ab81d554ebbe88c79ab5975992d79ba08 # v3
       with:
         timeout_minutes: 120
diff --git a/FirebaseSessions/Tests/Unit/FirebaseSessionsTests+BaseBehaviors.swift b/FirebaseSessions/Tests/Unit/FirebaseSessionsTests+BaseBehaviors.swift
index 2c453a4518a..c1b02cc38aa 100644
--- a/FirebaseSessions/Tests/Unit/FirebaseSessionsTests+BaseBehaviors.swift
+++ b/FirebaseSessions/Tests/Unit/FirebaseSessionsTests+BaseBehaviors.swift
@@ -87,7 +87,7 @@ final class FirebaseSessionsTestsBase_BaseBehaviors: FirebaseSessionsTestsBase {
     // We wanted to make sure that since we've introduced promises,
     // once the promise has been fulfilled, that .then'ing on the promise
     // in future initiations still results in a log
-    func test_multipleInitiations_logsSessionEventEachInitiation() {
+    @MainActor func test_multipleInitiations_logsSessionEventEachInitiation() {
       var loggedCount = 0
       var lastLoggedSessionID = ""
       let loggedTwiceExpectation = expectation(description: "Sessions SDK logged events twice")
diff --git a/FirebaseSessions/Tests/Unit/InitiatorTests.swift b/FirebaseSessions/Tests/Unit/InitiatorTests.swift
index c3b17fb3dde..ebb6be2b5bc 100644
--- a/FirebaseSessions/Tests/Unit/InitiatorTests.swift
+++ b/FirebaseSessions/Tests/Unit/InitiatorTests.swift
@@ -58,7 +58,7 @@ class InitiatorTests: XCTestCase {
     XCTAssert(initiateCalled)
   }
 
-  func test_appForegrounded_initiatesNewSession() throws {
+  @MainActor func test_appForegrounded_initiatesNewSession() throws {
     // Given
     var pausedClock = date
     let initiator = SessionInitiator(
diff --git a/FirebaseSessions/Tests/Unit/Library/LifecycleNotifications.swift b/FirebaseSessions/Tests/Unit/Library/LifecycleNotifications.swift
index 80c6f7c38f9..e2ea9d54e9d 100644
--- a/FirebaseSessions/Tests/Unit/Library/LifecycleNotifications.swift
+++ b/FirebaseSessions/Tests/Unit/Library/LifecycleNotifications.swift
@@ -37,18 +37,7 @@ import Dispatch
 #endif // swift(>=5.9)
 
 extension XCTestCase {
-  func postBackgroundedNotification() {
-    // On Catalyst, the notifications can only be called on a the main thread
-    if Thread.isMainThread {
-      postBackgroundedNotificationInternal()
-    } else {
-      DispatchQueue.main.sync {
-        self.postBackgroundedNotificationInternal()
-      }
-    }
-  }
-
-  private func postBackgroundedNotificationInternal() {
+  @MainActor func postBackgroundedNotification() {
     let notificationCenter = NotificationCenter.default
     #if os(iOS) || os(tvOS)
       notificationCenter.post(name: UIApplication.didEnterBackgroundNotification, object: nil)
@@ -74,18 +63,7 @@ extension XCTestCase {
     #endif // swift(>=5.9)
   }
 
-  func postForegroundedNotification() {
-    // On Catalyst, the notifications can only be called on a the main thread
-    if Thread.isMainThread {
-      postForegroundedNotificationInternal()
-    } else {
-      DispatchQueue.main.sync {
-        self.postForegroundedNotificationInternal()
-      }
-    }
-  }
-
-  private func postForegroundedNotificationInternal() {
+  @MainActor func postForegroundedNotification() {
     let notificationCenter = NotificationCenter.default
     #if os(iOS) || os(tvOS)
       notificationCenter.post(name: UIApplication.didBecomeActiveNotification, object: nil)