diff --git a/src/transformState.js b/src/transformState.js
index df970549..bb92e07d 100644
--- a/src/transformState.js
+++ b/src/transformState.js
@@ -5,17 +5,23 @@
  * @param {Object[]} actions
  */
 function transformState(state, actions) {
+  const actionTypes = {
+    addProperties: 'addProperties',
+    removeProperties: 'removeProperties',
+    clear: 'clear',
+  };
+
   for (const action of actions) {
     switch (action.type) {
-      case 'addProperties':
+      case actionTypes.addProperties:
         Object.assign(state, action.extraData);
         break;
 
-      case 'removeProperties':
+      case actionTypes.removeProperties:
         action.keysToRemove.forEach((key) => delete state[key]);
         break;
 
-      case 'clear':
+      case actionTypes.clear:
         Object.keys(state).forEach((key) => delete state[key]);
         break;