diff --git a/Mac/Inspector/BuiltinSmartFeedInspectorViewController.swift b/Mac/Inspector/BuiltinSmartFeedInspectorViewController.swift
index 3c6c7b908..72bca9099 100644
--- a/Mac/Inspector/BuiltinSmartFeedInspectorViewController.swift
+++ b/Mac/Inspector/BuiltinSmartFeedInspectorViewController.swift
@@ -8,7 +8,7 @@
 
 import AppKit
 
-final class BuiltinSmartFeedInspectorViewController: NSViewController, Inspector {
+@MainActor final class BuiltinSmartFeedInspectorViewController: NSViewController, Inspector {
 
 	@IBOutlet var nameTextField: NSTextField?
 	@IBOutlet weak var smartFeedImageView: NSImageView!
diff --git a/Mac/Inspector/FolderInspectorViewController.swift b/Mac/Inspector/FolderInspectorViewController.swift
index 63f76b0d7..6e12f248d 100644
--- a/Mac/Inspector/FolderInspectorViewController.swift
+++ b/Mac/Inspector/FolderInspectorViewController.swift
@@ -10,7 +10,7 @@ import AppKit
 import Account
 import RSCore
 
-final class FolderInspectorViewController: NSViewController, Inspector {
+@MainActor final class FolderInspectorViewController: NSViewController, Inspector {
 
 	@IBOutlet var nameTextField: NSTextField?
 	@IBOutlet weak var folderImageView: NSImageView!
diff --git a/Mac/Inspector/InspectorWindowController.swift b/Mac/Inspector/InspectorWindowController.swift
index 2686f86c4..078de1439 100644
--- a/Mac/Inspector/InspectorWindowController.swift
+++ b/Mac/Inspector/InspectorWindowController.swift
@@ -8,7 +8,7 @@
 
 import AppKit
 
-protocol Inspector: AnyObject {
+@MainActor protocol Inspector: AnyObject {
 
 	var objects: [Any]? { get set }
 	var isFallbackInspector: Bool { get } // Can handle nothing-to-inspect or unexpected type of objects.
@@ -20,7 +20,7 @@ protocol Inspector: AnyObject {
 typealias InspectorViewController = Inspector & NSViewController
 
 
-final class InspectorWindowController: NSWindowController {
+@MainActor final class InspectorWindowController: NSWindowController {
 
 	class var shouldOpenAtStartup: Bool {
 		return UserDefaults.standard.bool(forKey: DefaultsKey.windowIsOpen)
diff --git a/Mac/Inspector/NothingInspectorViewController.swift b/Mac/Inspector/NothingInspectorViewController.swift
index 376e6a594..168513e5e 100644
--- a/Mac/Inspector/NothingInspectorViewController.swift
+++ b/Mac/Inspector/NothingInspectorViewController.swift
@@ -8,7 +8,7 @@
 
 import AppKit
 
-final class NothingInspectorViewController: NSViewController, Inspector {
+@MainActor final class NothingInspectorViewController: NSViewController, Inspector {
 
 	@IBOutlet var nothingTextField: NSTextField?
 	@IBOutlet var multipleTextField: NSTextField?
diff --git a/Mac/Inspector/WebFeedInspectorViewController.swift b/Mac/Inspector/WebFeedInspectorViewController.swift
index 58c24b254..123961828 100644
--- a/Mac/Inspector/WebFeedInspectorViewController.swift
+++ b/Mac/Inspector/WebFeedInspectorViewController.swift
@@ -11,7 +11,7 @@ import Articles
 import Account
 import UserNotifications
 
-final class WebFeedInspectorViewController: NSViewController, Inspector {
+@MainActor final class WebFeedInspectorViewController: NSViewController, Inspector {
 
 	@IBOutlet weak var iconView: IconView!
 	@IBOutlet weak var nameTextField: NSTextField?