diff --git a/Packages/Qwertyyb_ShiftKeyUpChecker/Sources/ShiftKeyUpChecker/ShiftKeyUpChecker.swift b/Packages/Qwertyyb_ShiftKeyUpChecker/Sources/ShiftKeyUpChecker/ShiftKeyUpChecker.swift
index edaaeb44..82d2f3e2 100644
--- a/Packages/Qwertyyb_ShiftKeyUpChecker/Sources/ShiftKeyUpChecker/ShiftKeyUpChecker.swift
+++ b/Packages/Qwertyyb_ShiftKeyUpChecker/Sources/ShiftKeyUpChecker/ShiftKeyUpChecker.swift
@@ -39,6 +39,7 @@ public struct ShiftKeyUpChecker {
   private var shiftIsBeingPressed = false
 
   private mutating func checkModifierKeyUp(event: NSEvent) -> Bool {
+    guard checkKeyCode.contains(event.keyCode) else { return false }
     if event.type == .flagsChanged,
        event.modifierFlags.intersection(.deviceIndependentFlagsMask) == .init(rawValue: 0),
        Date() - lastTime <= delayInterval, shiftIsBeingPressed