diff --git a/src/Music.ts b/src/Music.ts
index d1ec5a5..b456041 100644
--- a/src/Music.ts
+++ b/src/Music.ts
@@ -106,9 +106,9 @@ export class Music {
     const { audio, isPlaying } = this;
 
     const genTime = audio.currentTime;
-    this.deltaTime = genTime - this.__prevAudioTime;
 
     if ( isPlaying ) {
+      this.deltaTime = genTime - this.__prevAudioTime;
       this.time += this.deltaTime;
 
       const buffer = this.__bufferPool.next();
@@ -125,6 +125,8 @@ export class Music {
       bufferSource.start( audio.currentTime, audio.currentTime - genTime );
       this.__prevBufferSource = bufferSource;
     } else {
+      this.deltaTime = 0.0;
+
       this.__prevBufferSource?.stop( audio.currentTime );
       this.__prevBufferSource = null;
     }
diff --git a/src/entities/Cube.ts b/src/entities/Cube.ts
index 95dc640..23dcb1a 100644
--- a/src/entities/Cube.ts
+++ b/src/entities/Cube.ts
@@ -17,13 +17,15 @@ export class Cube {
   public constructor() {
     this.entity = new Entity();
 
-    this.entity.transform.rotation = Quaternion.fromAxisAngle(
+    const rot0 = Quaternion.fromAxisAngle(
       new Vector3( [ 1.0, 0.0, 0.0 ] ),
       0.4,
     ).multiply( Quaternion.fromAxisAngle(
       new Vector3( [ 0.0, 0.0, 1.0 ] ),
       0.4,
     ) );
+
+    this.entity.transform.rotation = rot0;
     this.entity.transform.scale = this.entity.transform.scale.scale( 0.8 );
 
     this.geometry = this.__createGeometry();
@@ -37,9 +39,9 @@ export class Cube {
     this.entity.components.push( this.mesh );
 
     this.entity.components.push( new Lambda( {
-      onUpdate: ( { deltaTime } ) => {
-        this.entity.transform.rotation = this.entity.transform.rotation.multiply(
-          Quaternion.fromAxisAngle( new Vector3( [ 0.0, 1.0, 0.0 ] ), deltaTime )
+      onUpdate: ( { time } ) => {
+        this.entity.transform.rotation = rot0.multiply(
+          Quaternion.fromAxisAngle( new Vector3( [ 0.0, 1.0, 0.0 ] ), time )
         );
       },
       visible: false,