diff --git a/src/core/animations/keyframe-builder.ts b/src/core/animations/keyframe-builder.ts
index ece0e132..dcd96f2a 100644
--- a/src/core/animations/keyframe-builder.ts
+++ b/src/core/animations/keyframe-builder.ts
@@ -130,7 +130,7 @@ export class KeyframeBuilder {
 	private createNormalizedKeyframes(keyframes: Keyframe[]): NumericKeyframe[] {
 		return keyframes
 			.filter((kf): kf is Keyframe & { start: number; length: number } => typeof kf.start === "number" && typeof kf.length === "number")
-			.toSorted((a, b) => a.start - b.start)
+			.sort((a, b) => a.start - b.start)
 			.map(keyframe => ({
 				start: keyframe.start,
 				length: keyframe.length,
diff --git a/src/core/animations/opacity-keyframes.ts b/src/core/animations/opacity-keyframes.ts
index 53e1f834..33aa7f12 100644
--- a/src/core/animations/opacity-keyframes.ts
+++ b/src/core/animations/opacity-keyframes.ts
@@ -149,7 +149,7 @@ export function upsertOpacityPoint(
 	const time = snapOpacityTime(localTime, clipLength, fps);
 	const existing = findOpacityPoint(points, time, fps);
 	const next = existing ? points.map(point => (point === existing ? { time: point.time, value } : point)) : [...points, { time, value }];
-	return next.toSorted((a, b) => a.time - b.time);
+	return next.sort((a, b) => a.time - b.time);
 }
 
 export function removeOpacityPoint(points: readonly OpacityPoint[], localTime: number, fps: number): OpacityPoint[] {