diff --git a/src/core/observer.ts b/src/core/observer.ts
index 4f9f2a45..398004aa 100644
--- a/src/core/observer.ts
+++ b/src/core/observer.ts
@@ -20,7 +20,6 @@
 export class Observer {
   rev: number = 1;
   allowMutations: boolean = true;
-  dirty: boolean = false;
   weakMap: WeakMap<any, any> = new WeakMap();
 
   notifyCB() {}