diff --git a/packages/runtime-html/src/observation/observer-locator.ts b/packages/runtime-html/src/observation/observer-locator.ts
index c769c4e50e..1e99452c8d 100644
--- a/packages/runtime-html/src/observation/observer-locator.ts
+++ b/packages/runtime-html/src/observation/observer-locator.ts
@@ -117,7 +117,7 @@ export class TargetObserverLocator implements ITargetObserverLocator {
       case 'css':
         return new StyleAttributeAccessor(scheduler, flags, obj as HTMLElement);
       case 'model':
-        return new SetterObserver(lifecycle, flags, obj as Node & IIndexable, propertyName);
+        return new SetterObserver(flags, obj as Node & IIndexable, propertyName);
       case 'role':
         return new DataAttributeAccessor(scheduler, flags, obj as HTMLElement, propertyName);
       default:
diff --git a/packages/runtime/src/observation/binding-context.ts b/packages/runtime/src/observation/binding-context.ts
index 601d8e00b9..639b5a2356 100644
--- a/packages/runtime/src/observation/binding-context.ts
+++ b/packages/runtime/src/observation/binding-context.ts
@@ -21,7 +21,11 @@ const enum RuntimeError {
 const marker = Object.freeze({});
 
 /** @internal */
-export class InternalObserversLookup {
+export class InternalObserversLookup implements ObserversLookup {
+  [x: string]: PropertyObserver;
+  [y: number]: PropertyObserver;
+
+  // @ts-expect-error
   public getOrCreate(
     this: { [key: string]: PropertyObserver },
     lifecycle: ILifecycle,
@@ -30,7 +34,7 @@ export class InternalObserversLookup {
     key: string,
   ): PropertyObserver {
     if (this[key] === void 0) {
-      this[key] = new SetterObserver(lifecycle, flags, obj, key);
+      this[key] = new SetterObserver(flags, obj, key);
     }
     return this[key];
   }
diff --git a/packages/runtime/src/observation/observer-locator.ts b/packages/runtime/src/observation/observer-locator.ts
index b561376956..2407b25b42 100644
--- a/packages/runtime/src/observation/observer-locator.ts
+++ b/packages/runtime/src/observation/observer-locator.ts
@@ -248,7 +248,7 @@ export class ObserverLocator implements IObserverLocator {
 
       return createComputedObserver(flags, this, this.dirtyChecker, this.lifecycle, obj, propertyName, descriptor);
     }
-    return new SetterObserver(this.lifecycle, flags, obj, propertyName);
+    return new SetterObserver(flags, obj, propertyName);
   }
 }
 
diff --git a/packages/runtime/src/observation/setter-observer.ts b/packages/runtime/src/observation/setter-observer.ts
index 04856a4785..2aaf2e4c65 100644
--- a/packages/runtime/src/observation/setter-observer.ts
+++ b/packages/runtime/src/observation/setter-observer.ts
@@ -22,7 +22,6 @@ export class SetterObserver {
   public type: AccessorType = AccessorType.Obj;
 
   public constructor(
-    public readonly lifecycle: ILifecycle,
     flags: LifecycleFlags,
     public readonly obj: IIndexable,
     public readonly propertyKey: string,
@@ -59,6 +58,14 @@ export class SetterObserver {
   }
 
   public subscribe(subscriber: ISubscriber): void {
+    if (this.observing === false) {
+      this.start();
+    }
+
+    this.addSubscriber(subscriber);
+  }
+
+  public start(): this {
     if (this.observing === false) {
       this.observing = true;
       this.currentValue = this.obj[this.propertyKey];
@@ -81,7 +88,20 @@ export class SetterObserver {
         Reporter.write(1, this.propertyKey, this.obj);
       }
     }
+    return this;
+  }
 
-    this.addSubscriber(subscriber);
+  public stop(): this {
+    if (this.observing) {
+      Reflect.defineProperty(this.obj, this.propertyKey, {
+        enumerable: true,
+        configurable: true,
+        writable: true,
+        value: this.currentValue,
+      });
+      this.observing = false;
+      // todo(bigopon/fred): add .removeAllSubscribers()
+    }
+    return this;
   }
 }