diff --git a/src/browser/ui/dom/getEventModifierState.js b/src/browser/ui/dom/getEventModifierState.js
index 46e91a0fc51..8ec8cad8da4 100644
--- a/src/browser/ui/dom/getEventModifierState.js
+++ b/src/browser/ui/dom/getEventModifierState.js
@@ -25,10 +25,10 @@
  */
 
 var modifierKeyToProp = {
-  'alt': 'altKey',
-  'control': 'ctrlKey',
-  'meta': 'metaKey',
-  'shift': 'shiftKey'
+  'Alt': 'altKey',
+  'Control': 'ctrlKey',
+  'Meta': 'metaKey',
+  'Shift': 'shiftKey'
 };
 
 // IE8 does not implement getModifierState so we simply map it to the only
@@ -41,7 +41,7 @@ function modifierStateGetter(keyArg) {
   if (nativeEvent.getModifierState) {
     return nativeEvent.getModifierState(keyArg);
   }
-  var keyProp = modifierKeyToProp[keyArg.toLowerCase()];
+  var keyProp = modifierKeyToProp[keyArg];
   return keyProp && nativeEvent[keyProp];
 }