diff --git a/CHANGELOG-PRERELEASE-jp.md b/CHANGELOG-PRERELEASE-jp.md
index 4c9478c4..96b648cb 100644
--- a/CHANGELOG-PRERELEASE-jp.md
+++ b/CHANGELOG-PRERELEASE-jp.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - [#1522] `Convert Constraints` がアニメーション参照を変換できない問題を修正
+- [#1528] `Merge Animator` が `アバターのWrite Defaults設定に合わせる` 設定を無視し、常に合わせてしまう問題を修正
 
 ### Changed
 
diff --git a/CHANGELOG-PRERELEASE.md b/CHANGELOG-PRERELEASE.md
index 9b9c3450..3beec340 100644
--- a/CHANGELOG-PRERELEASE.md
+++ b/CHANGELOG-PRERELEASE.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - [#1522] `Convert Constraints` failed to convert animation references
+- [#1528] `Merge Animator` ignored the `Match Avatar Write Defaults` setting and always matched
 
 ### Changed
 
diff --git a/Editor/MergeAnimatorProcessor.cs b/Editor/MergeAnimatorProcessor.cs
index b331ee59..84060558 100644
--- a/Editor/MergeAnimatorProcessor.cs
+++ b/Editor/MergeAnimatorProcessor.cs
@@ -137,6 +137,11 @@ namespace nadena.dev.modular_avatar.core.editor
                 return;
             }
 
+            if (!merge.matchAvatarWriteDefaults)
+            {
+                initialWriteDefaults = null;
+            }
+
             var vac = context.PluginBuildContext.Extension<VirtualControllerContext>();
 
             if (!vac.Controllers.TryGetValue(merge, out var clonedController)) return;
diff --git a/UnitTests~/MergeAnimatorTests/WriteDefaults/TestSet_true.controller b/UnitTests~/MergeAnimatorTests/WriteDefaults/TestSet_true.controller
index 138df46c..595ae983 100644
--- a/UnitTests~/MergeAnimatorTests/WriteDefaults/TestSet_true.controller
+++ b/UnitTests~/MergeAnimatorTests/WriteDefaults/TestSet_true.controller
@@ -272,7 +272,7 @@ AnimatorController:
     m_SyncedLayerAffectsTiming: 0
     m_Controller: {fileID: 9100000}
   - serializedVersion: 5
-    m_Name: 1_Additive
+    m_Name: X_Additive
     m_StateMachine: {fileID: 2859792172588103306}
     m_Mask: {fileID: 0}
     m_Motions: []
@@ -284,7 +284,7 @@ AnimatorController:
     m_SyncedLayerAffectsTiming: 0
     m_Controller: {fileID: 9100000}
   - serializedVersion: 5
-    m_Name: 1_SingleMotion
+    m_Name: X_SingleMotion
     m_StateMachine: {fileID: 7425114331284477142}
     m_Mask: {fileID: 0}
     m_Motions: []
@@ -360,7 +360,7 @@ AnimatorStateMachine:
   m_CorrespondingSourceObject: {fileID: 0}
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
-  m_Name: 1_Additive
+  m_Name: X_Additive
   m_ChildStates:
   - serializedVersion: 1
     m_State: {fileID: -3889880041459077057}
@@ -459,7 +459,7 @@ AnimatorStateMachine:
   m_CorrespondingSourceObject: {fileID: 0}
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
-  m_Name: 1_SingleMotion
+  m_Name: X_SingleMotion
   m_ChildStates:
   - serializedVersion: 1
     m_State: {fileID: -2269384398499780410}
diff --git a/UnitTests~/MergeAnimatorTests/WriteDefaults/WriteDefaultsMergeTests.cs b/UnitTests~/MergeAnimatorTests/WriteDefaults/WriteDefaultsMergeTests.cs
index 921349b6..e67035fd 100644
--- a/UnitTests~/MergeAnimatorTests/WriteDefaults/WriteDefaultsMergeTests.cs
+++ b/UnitTests~/MergeAnimatorTests/WriteDefaults/WriteDefaultsMergeTests.cs
@@ -13,24 +13,33 @@ namespace UnitTests.MergeAnimatorTests.WriteDefaults
         [Test]
         public void TestWriteDefaultsMerge(
             [Values("WD_OFF", "WD_ON", "Ambiguous")] string scenario,
-            [Values(true, false)] bool mergeSetMode
+            [Values(true, false)] bool mergeAnimatorInitialState,
+            [Values(true, false)] bool matchWD
         )
         {
-            bool? wdMode;
+            bool? baseFxWdState;
             switch (scenario)
             {
-                case "WD_OFF": wdMode = false; break;
-                case "WD_ON": wdMode = true; break;
-                default: wdMode = null; break;
+                case "WD_OFF": baseFxWdState = false; break;
+                case "WD_ON": baseFxWdState = true; break;
+                default: baseFxWdState = null; break;
             }
+
+            // If the base layer is ambiguous and WD is disabled, the only thing we can assert is that nothing changed.
+            // This is kind of a pain, so... TODO
+            if (baseFxWdState == null && !matchWD) return;
             
             var root = CreateRoot(scenario);
             var m1 = CreateChild(root, "m1").AddComponent<ModularAvatarMergeAnimator>();
             var m2 = CreateChild(root, "m2").AddComponent<ModularAvatarMergeAnimator>();
             
+            // m1 provides the base FX layer for the avatar
             m1.animator = LoadAsset<AnimatorController>(scenario + ".controller");
             m1.mergeAnimatorMode = MergeAnimatorMode.Replace;
-            m2.animator = LoadAsset<AnimatorController>("TestSet_" + mergeSetMode + ".controller");
+            
+            m2.animator = LoadAsset<AnimatorController>("TestSet_" + mergeAnimatorInitialState + ".controller");
+            m2.mergeAnimatorMode = MergeAnimatorMode.Append;
+            m2.matchAvatarWriteDefaults = matchWD;
             
             AvatarProcessor.ProcessAvatar(root);
             
@@ -46,8 +55,14 @@ namespace UnitTests.MergeAnimatorTests.WriteDefaults
                 
                 switch (layer.Name[0])
                 {
-                    case 'M': expectedState = wdMode ?? mergeSetMode; break;
-                    case 'X': expectedState = mergeSetMode; break;
+                    // M layers: We expect to "M"atch WD state if the merge component is set to match WD (and a WD mode
+                    // was determined); otherwise, it should keep its original state.
+                    case 'M':
+                    {
+                        expectedState = (matchWD ? baseFxWdState : null) ?? mergeAnimatorInitialState;
+                        break;
+                    }
+                    case 'X': expectedState = mergeAnimatorInitialState; break;
                     default: continue;
                 }