diff --git a/src/lights/RectAreaLight.ts b/src/lights/RectAreaLight.ts
index 5347b78..53fa0e5 100644
--- a/src/lights/RectAreaLight.ts
+++ b/src/lights/RectAreaLight.ts
@@ -18,7 +18,7 @@ export default defineComponent({
     const watchProps = ['width', 'height']
     watchProps.forEach(p => {
       // @ts-ignore
-      watch(() => this[p], () => { light[p] = this[p] })
+      watch(() => this[p], (value) => { light[p] = value })
     })
 
     if (this.helper) {
diff --git a/src/lights/SpotLight.ts b/src/lights/SpotLight.ts
index e24475a..8dcd72f 100644
--- a/src/lights/SpotLight.ts
+++ b/src/lights/SpotLight.ts
@@ -17,7 +17,7 @@ export default defineComponent({
     const watchProps = ['angle', 'decay', 'distance', 'penumbra']
     watchProps.forEach(p => {
       // @ts-ignore
-      watch(() => this[p], () => { light[p] = this[p] })
+      watch(() => this[p], (value) => { light[p] = value })
     })
 
     this.initLight(light)