diff --git a/packages/stage-ui-live2d/src/utils/eye-motions.ts b/packages/stage-ui-live2d/src/utils/eye-motions.ts
index e97a8a3fd..e89e35e12 100644
--- a/packages/stage-ui-live2d/src/utils/eye-motions.ts
+++ b/packages/stage-ui-live2d/src/utils/eye-motions.ts
@@ -28,5 +28,5 @@ export function randomSaccadeInterval(): number {
       return EYE_SACCADE_INT_P[i][1] + Math.random() * EYE_SACCADE_INT_STEP
     }
   }
-  return EYE_SACCADE_INT_P.at(-1)[1] + Math.random() * EYE_SACCADE_INT_STEP
+  return EYE_SACCADE_INT_P.at(-1)![1] + Math.random() * EYE_SACCADE_INT_STEP
 }