diff --git a/ext/bg/js/settings/keyboard-mouse-input-field.js b/ext/bg/js/settings/keyboard-mouse-input-field.js
index 94709313..09477519 100644
--- a/ext/bg/js/settings/keyboard-mouse-input-field.js
+++ b/ext/bg/js/settings/keyboard-mouse-input-field.js
@@ -46,7 +46,8 @@ class KeyboardMouseInputField extends EventDispatcher {
         this._keySupported = keySupported;
         this.setInput(key, modifiers);
         const events = [
-            [this._inputNode, 'keydown', this._onModifierKeyDown.bind(this), false]
+            [this._inputNode, 'keydown', this._onModifierKeyDown.bind(this), false],
+            [this._inputNode, 'keyup', this._onModifierKeyUp.bind(this), false]
         ];
         if (mouseModifiersSupported && this._mouseButton !== null) {
             events.push(
@@ -152,6 +153,10 @@ class KeyboardMouseInputField extends EventDispatcher {
         }
     }
 
+    _onModifierKeyUp(e) {
+        e.preventDefault();
+    }
+
     _onMouseButtonMouseDown(e) {
         e.preventDefault();
         this._addModifiers(DocumentUtil.getActiveButtons(e));