diff --git a/CHANGELOG-PRERELEASE.md b/CHANGELOG-PRERELEASE.md
index aec1b1285..9a65ffa14 100644
--- a/CHANGELOG-PRERELEASE.md
+++ b/CHANGELOG-PRERELEASE.md
@@ -19,9 +19,15 @@ The format is based on [Keep a Changelog].
 
 ### Fixed
 - Prefab blinks when we see editor of PrefabSafeSet of prefab asset `#645`
+- Fixes in 1.5.9 `#654`
 
 ### Security
 
+## [1.5.9] - 2023-10-29
+## [1.5.9-rc.1] - 2023-10-28
+### Fixed
+- Animation clip length can be changed [`#647`](https://github.com/anatawa12/AvatarOptimizer/pull/647)
+
 ## [1.6.0-beta.1] - 2023-10-25
 ### Added
 - Public API for registering component information [`#623`](https://github.com/anatawa12/AvatarOptimizer/pull/623)
@@ -952,7 +958,9 @@ This release is mistake.
 - Clear Endpoint Position
 
 [Unreleased]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.6.0-beta.1...HEAD
-[1.6.0-beta.1]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.8...v1.6.0-beta.1
+[1.6.0-beta.1]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.9...v1.6.0-beta.1
+[1.5.9]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.9-rc.1...v1.5.9
+[1.5.9-rc.1]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.8...v1.5.9-rc.1
 [1.5.8]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.8-rc.1...v1.5.8
 [1.5.8-rc.1]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.7...v1.5.8-rc.1
 [1.5.7]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.7-beta.1...v1.5.7
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad134babe..2a9135977 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,10 @@ The format is based on [Keep a Changelog].
 
 ### Security
 
+## [1.5.9] - 2023-10-29
+### Fixed
+- Animation clip length can be changed [`#647`](https://github.com/anatawa12/AvatarOptimizer/pull/647)
+
 ## [1.5.8] - 2023-10-20
 ### Fixed
 - warning about VRCTestMarker when Build & Test [`#628`](https://github.com/anatawa12/AvatarOptimizer/pull/628)
@@ -629,7 +633,8 @@ The format is based on [Keep a Changelog].
 - Merge Bone
 - Clear Endpoint Position
 
-[Unreleased]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.8...HEAD
+[Unreleased]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.9...HEAD
+[1.5.9]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.8...v1.5.9
 [1.5.8]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.7...v1.5.8
 [1.5.7]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.6...v1.5.7
 [1.5.6]: https://github.com/anatawa12/AvatarOptimizer/compare/v1.5.5...v1.5.6
diff --git a/Editor/ObjectMapping/ObjectMappingContext.cs b/Editor/ObjectMapping/ObjectMappingContext.cs
index 22dba13e1..065f90f3a 100644
--- a/Editor/ObjectMapping/ObjectMappingContext.cs
+++ b/Editor/ObjectMapping/ObjectMappingContext.cs
@@ -131,6 +131,15 @@ private Object CustomClone(Object o)
                 var newClip = new AnimationClip();
                 newClip.name = "rebased " + clip.name;
 
+                // copy m_UseHighQualityCurve with SerializedObject since m_UseHighQualityCurve doesn't have public API
+                using (var serializedClip = new SerializedObject(clip))
+                using (var serializedNewClip = new SerializedObject(newClip))
+                {
+                    serializedNewClip.FindProperty("m_UseHighQualityCurve")
+                        .boolValue = serializedClip.FindProperty("m_UseHighQualityCurve").boolValue;
+                    serializedNewClip.ApplyModifiedPropertiesWithoutUndo();
+                }
+
                 foreach (var binding in AnimationUtility.GetCurveBindings(clip))
                 {
                     var newBindings = _mapping.MapBinding(binding);
@@ -169,6 +178,16 @@ private Object CustomClone(Object o)
                     }
                 }
 
+                // ReSharper disable once CompareOfFloatsByEqualityOperator
+                if (newClip.length != clip.length)
+                {
+                    // if newClip has less properties than original clip (especially for no properties), 
+                    // length of newClip can be changed which is bad.
+                    newClip.SetCurve(
+                        "$AvatarOptimizerClipLengthDummy$", typeof(GameObject), "m_IsActive",
+                        AnimationCurve.Constant(clip.length, clip.length, 1f));
+                }
+
                 newClip.wrapMode = clip.wrapMode;
                 newClip.legacy = clip.legacy;
                 newClip.frameRate = clip.frameRate;