diff --git a/Source/Modules/SessionCtl_Core.swift b/Source/Modules/SessionCtl_Core.swift
index b89de892..6201df83 100644
--- a/Source/Modules/SessionCtl_Core.swift
+++ b/Source/Modules/SessionCtl_Core.swift
@@ -40,6 +40,9 @@ public class SessionCtl: IMKInputController {
   /// 用來標記當前副本是否已處於活動狀態。
   public var isActivated = false
 
+  /// 當前副本的客體是否是輸入法本體？
+  public var isServingIMEItself: Bool = false
+
   // MARK: -
 
   /// 當前 Caps Lock 按鍵是否被摁下。
@@ -165,9 +168,7 @@ public class SessionCtl: IMKInputController {
 extension SessionCtl {
   /// 強制重設當前鍵盤佈局、使其與偏好設定同步。
   public func setKeyLayout() {
-    guard let client = client(), let myID = Bundle.main.bundleIdentifier, !myID.isEmpty,
-      clientBundleIdentifier != myID
-    else { return }
+    guard let client = client(), !isServingIMEItself else { return }
 
     DispatchQueue.main.async { [self] in
       if isASCIIMode, IMKHelper.isDynamicBasicKeyboardLayoutEnabled {
@@ -198,12 +199,13 @@ extension SessionCtl {
 
 extension SessionCtl {
   /// 啟用輸入法時，會觸發該函式。
-  /// - Parameter sender: 呼叫了該函式的客體（無須使用）。
+  /// - Parameter sender: 呼叫了該函式的客體。
   public override func activateServer(_ sender: Any!) {
     _ = sender  // 防止格式整理工具毀掉與此對應的參數。
-    DispatchQueue.main.async {
+    DispatchQueue.main.async { [self] in
       if let senderBundleID: String = (sender as? IMKTextInput)?.bundleIdentifier() {
         vCLog("activateServer(\(senderBundleID))")
+        isServingIMEItself = Bundle.main.bundleIdentifier == senderBundleID
       }
     }
     DispatchQueue.main.async { [self] in
diff --git a/Source/Modules/SessionCtl_HandleStates.swift b/Source/Modules/SessionCtl_HandleStates.swift
index 0f4c25d4..723a5a5a 100644
--- a/Source/Modules/SessionCtl_HandleStates.swift
+++ b/Source/Modules/SessionCtl_HandleStates.swift
@@ -121,7 +121,7 @@ extension SessionCtl {
     if buffer.isEmpty {
       return
     }
-    if let myID = Bundle.main.bundleIdentifier, let clientID = client.bundleIdentifier(), myID == clientID {
+    if isServingIMEItself {
       DispatchQueue.main.async {
         client.insertText(
           buffer, replacementRange: NSRange(location: NSNotFound, length: NSNotFound)
@@ -137,7 +137,7 @@ extension SessionCtl {
   /// 把 setMarkedText 包裝一下，按需啟用 GCD。
   public func doSetMarkedText(_ string: Any!, selectionRange: NSRange, replacementRange: NSRange) {
     guard isActivated, let client = client() else { return }
-    if let myID = Bundle.main.bundleIdentifier, let clientID = client.bundleIdentifier(), myID == clientID {
+    if isServingIMEItself {
       DispatchQueue.main.async {
         client.setMarkedText(string, selectionRange: selectionRange, replacementRange: replacementRange)
       }