diff --git a/src/color.swift b/src/color.swift
index 9901e76..3779d1c 100644
--- a/src/color.swift
+++ b/src/color.swift
@@ -11,8 +11,10 @@ public func nsColorToString(_ color: NSColor) -> String? {
   return String(format: "#%02X%02X%02X%02X", red, green, blue, alpha)
 }
 
+@MainActor
 private var colorMap = [String: String]()
 
+@MainActor
 func getAccentColor(_ id: String) -> String {
   if let cachedColor = colorMap[id] {
     return cachedColor
diff --git a/src/config/menu.swift b/src/config/menu.swift
index 21e89f6..74fb8a6 100644
--- a/src/config/menu.swift
+++ b/src/config/menu.swift
@@ -1,6 +1,7 @@
 import Cocoa
 import Fcitx
 
+@MainActor
 func restartAndReconnect(_ actionBetween: (() -> Void)? = nil) {
   stop_fcitx_thread()
   actionBetween?()
diff --git a/src/controller.swift b/src/controller.swift
index 324140b..9cd262e 100644
--- a/src/controller.swift
+++ b/src/controller.swift
@@ -16,6 +16,7 @@ struct SyncResponse: Codable {
 let capsLock = 65536
 let shift = 131072
 
+@MainActor
 class FcitxInputController: IMKInputController {
   var uuid: ICUUID
   var appId: String
@@ -29,12 +30,13 @@ class FcitxInputController: IMKInputController {
 
   // A registry of live FcitxInputController objects.
   // Use NSHashTable to store weak references.
-  static var registry = NSHashTable<FcitxInputController>.weakObjects()
+  nonisolated(unsafe) static var registry = NSHashTable<FcitxInputController>.weakObjects()
 
   // A new InputController is created for each server-client
   // connection. We use the finest granularity here (one InputContext
   // for one IMKTextInput), and pass the bundle identifier to let
   // libfcitx handle the heavylifting.
+  @MainActor
   override init(server: IMKServer!, delegate: Any!, client: Any!) {
     if let client = client as? IMKTextInput {
       appId = client.bundleIdentifier() ?? ""
diff --git a/tests/testcolor.swift b/tests/testcolor.swift
index abc9045..6595805 100644
--- a/tests/testcolor.swift
+++ b/tests/testcolor.swift
@@ -17,11 +17,13 @@ func testGrayScale() {
   assert(nsColorToString(grayColor) == "#808080FF")
 }
 
+@MainActor
 func testGetAccentColor() {
   let accentColor = getAccentColor("com.apple.Notes")
   assert(accentColor == "#FCB827FF")
 }
 
+@MainActor
 @_cdecl("main")
 func main() -> Int {
   testGrayScale()