diff --git a/Packages/vChewing_MainAssembly/Sources/MainAssembly/IMEApp.swift b/Packages/vChewing_MainAssembly/Sources/MainAssembly/IMEApp.swift
index aa25feeb..6af55774 100644
--- a/Packages/vChewing_MainAssembly/Sources/MainAssembly/IMEApp.swift
+++ b/Packages/vChewing_MainAssembly/Sources/MainAssembly/IMEApp.swift
@@ -7,6 +7,7 @@
 // requirements defined in MIT License.
 
 import AppKit
+import Carbon
 import Shared
 
 // MARK: - Top-level Enums relating to Input Mode and Language Supports.
@@ -58,6 +59,11 @@ public enum IMEApp {
     .init(rawValue: PrefMgr.shared.mostRecentInputMode) ?? .imeModeNULL
   }
 
+  /// 當前鍵盤是否是 JIS 佈局
+  public static var isKeyboardJIS: Bool {
+    KBGetLayoutType(Int16(LMGetKbdType())) == kKeyboardJIS
+  }
+
   /// Fart or Beep?
   public static func buzz() {
     if PrefMgr.shared.isDebugModeEnabled {
diff --git a/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_HandleCandidate.swift b/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_HandleCandidate.swift
index 81d338e4..686e2d49 100644
--- a/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_HandleCandidate.swift
+++ b/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_HandleCandidate.swift
@@ -232,8 +232,7 @@ extension InputHandler {
     let ctrlShiftCMD: Bool = input.keyModifierFlags == [.control, .command, .shift]
     if ctrlShiftCMD || ctrlCMD {
       // 此處 JIS 鍵盤判定無法用於螢幕鍵盤。所以，螢幕鍵盤的場合，系統會依照 US 鍵盤的判定方案。
-      let isJIS: Bool = KBGetLayoutType(Int16(LMGetKbdType())) == kKeyboardJIS
-      switch (input.keyCode, isJIS) {
+      switch (input.keyCode, IMEApp.isKeyboardJIS) {
       case (30, true), (33, false):
         _ = ctlCandidate.highlightPreviousCandidate() ? {}() : delegate.callError("8B144DCD")
         return true
diff --git a/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_TriageInput.swift b/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_TriageInput.swift
index 101330d2..3e84d708 100644
--- a/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_TriageInput.swift
+++ b/Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_TriageInput.swift
@@ -164,8 +164,7 @@ public extension InputHandler {
       revolveCandidateWithBrackets: if ctrlShiftCMD || ctrlCMD {
         if state.type != .ofInputting { break revolveCandidateWithBrackets }
         // 此處 JIS 鍵盤判定無法用於螢幕鍵盤。所以，螢幕鍵盤的場合，系統會依照 US 鍵盤的判定方案。
-        let isJIS: Bool = KBGetLayoutType(Int16(LMGetKbdType())) == kKeyboardJIS
-        switch (input.keyCode, isJIS) {
+        switch (input.keyCode, IMEApp.isKeyboardJIS) {
         case (30, true), (33, false): return revolveCandidate(reverseOrder: true)
         case (42, true), (30, false): return revolveCandidate(reverseOrder: false)
         default: break