diff --git a/Mac/MainWindow/AddFeed/AddFeedController.swift b/Mac/MainWindow/AddFeed/AddFeedController.swift
index 941fca98b..38c27414b 100644
--- a/Mac/MainWindow/AddFeed/AddFeedController.swift
+++ b/Mac/MainWindow/AddFeed/AddFeedController.swift
@@ -22,7 +22,7 @@ import RSParser
 //   Else,
 //      display error sheet.
 
-class AddFeedController: AddFeedWindowControllerDelegate {
+@MainActor final class AddFeedController: AddFeedWindowControllerDelegate {
 
 	private let hostWindow: NSWindow
 	private var addFeedWindowController: AddFeedWindowController?
diff --git a/Mac/MainWindow/AddFeed/AddFeedWIndowController.swift b/Mac/MainWindow/AddFeed/AddFeedWIndowController.swift
index e574d7fa5..50ad03701 100644
--- a/Mac/MainWindow/AddFeed/AddFeedWIndowController.swift
+++ b/Mac/MainWindow/AddFeed/AddFeedWIndowController.swift
@@ -14,7 +14,7 @@ enum AddFeedWindowControllerType {
 	case redditFeed
 }
 
-protocol AddFeedWindowControllerDelegate: AnyObject {
+@MainActor protocol AddFeedWindowControllerDelegate: AnyObject {
 
 	// userEnteredURL will have already been validated and normalized.
 	func addFeedWindowController(_: AddFeedWindowController, userEnteredURL: URL, userEnteredTitle: String?, container: Container)
@@ -22,7 +22,7 @@ protocol AddFeedWindowControllerDelegate: AnyObject {
 	
 }
 
-protocol AddFeedWindowController {
+@MainActor protocol AddFeedWindowController {
 
 	var window: NSWindow? { get }
 	func runSheetOnWindow(_ hostWindow: NSWindow)
diff --git a/Mac/MainWindow/AddRedditFeedWindowController.swift b/Mac/MainWindow/AddRedditFeedWindowController.swift
index 55056ad34..0d07abccb 100644
--- a/Mac/MainWindow/AddRedditFeedWindowController.swift
+++ b/Mac/MainWindow/AddRedditFeedWindowController.swift
@@ -12,7 +12,7 @@ import RSTree
 import Articles
 import Account
 
-class AddRedditFeedWindowController : NSWindowController, AddFeedWindowController {
+@MainActor final class AddRedditFeedWindowController : NSWindowController, AddFeedWindowController {
 
 	@IBOutlet weak var typePopupButton: NSPopUpButton!
 	@IBOutlet weak var typeDescriptionLabel: NSTextField!