diff --git a/doric-js/index.d.ts b/doric-js/index.d.ts
index ecd2b229..f739fc84 100644
--- a/doric-js/index.d.ts
+++ b/doric-js/index.d.ts
@@ -422,7 +422,6 @@ declare module 'doric/lib/src/ui/animation' {
             get toRotation(): number;
     }
     export class AnimationSet implements IAnimation {
-            _duration: number;
             delay?: number;
             addAnimation(anim: IAnimation): void;
             get duration(): number;
diff --git a/doric-js/lib/src/ui/animation.d.ts b/doric-js/lib/src/ui/animation.d.ts
index 7ce73294..b5f103f1 100644
--- a/doric-js/lib/src/ui/animation.d.ts
+++ b/doric-js/lib/src/ui/animation.d.ts
@@ -114,7 +114,7 @@ export declare class RotationAnimation extends Animation {
 }
 export declare class AnimationSet implements IAnimation {
     private animations;
-    _duration: number;
+    private _duration;
     delay?: number;
     addAnimation(anim: IAnimation): void;
     get duration(): number;
diff --git a/doric-js/src/ui/animation.ts b/doric-js/src/ui/animation.ts
index b1c49de3..de0c713d 100644
--- a/doric-js/src/ui/animation.ts
+++ b/doric-js/src/ui/animation.ts
@@ -236,7 +236,7 @@ export class RotationAnimation extends Animation {
 
 export class AnimationSet implements IAnimation {
     private animations: IAnimation[] = []
-    _duration = 0
+    private _duration = 0
     delay?: number
     addAnimation(anim: IAnimation) {
         this.animations.push(anim)