diff --git a/src/final/01.extra-4.js b/src/final/01.extra-4.js
index 49c35acc..2a843e44 100644
--- a/src/final/01.extra-4.js
+++ b/src/final/01.extra-4.js
@@ -14,7 +14,7 @@ function countReducer(state, action) {
       }
     }
     default: {
-      throw new Error(`Unsupported action type: ${action.type}`)
+      throw new Error(`Unsupported action type: ${type}`)
     }
   }
 }