diff --git a/src/browser/ui/dom/getEventModifierState.js b/src/browser/ui/dom/getEventModifierState.js
index 8ec8cad8da4..39b2fadaaff 100644
--- a/src/browser/ui/dom/getEventModifierState.js
+++ b/src/browser/ui/dom/getEventModifierState.js
@@ -42,7 +42,7 @@ function modifierStateGetter(keyArg) {
     return nativeEvent.getModifierState(keyArg);
   }
   var keyProp = modifierKeyToProp[keyArg];
-  return keyProp && nativeEvent[keyProp];
+  return keyProp ? !!nativeEvent[keyProp] : false
 }
 
 function getEventModifierState(nativeEvent) {