diff --git a/Assets/MeshUtility/Editor/HumanoidEditor.cs b/Assets/MeshUtility/Editor/HumanoidEditor.cs
index dcdbbac630..f9a99cfc11 100644
--- a/Assets/MeshUtility/Editor/HumanoidEditor.cs
+++ b/Assets/MeshUtility/Editor/HumanoidEditor.cs
@@ -200,7 +200,7 @@ static void HorizontalFields(string label, params SerializedProperty[] props)
         static string GetDialogDir(UnityEngine.Object obj)
         {
             var prefab = PrefabUtility.GetCorrespondingObjectFromSource(obj);
-            if (prefab is null)
+            if (prefab == null)
             {
                 return null;
             }
diff --git a/Assets/MeshUtility/Runtime/Humanoid.cs b/Assets/MeshUtility/Runtime/Humanoid.cs
index 10db7335f1..c6d6194832 100644
--- a/Assets/MeshUtility/Runtime/Humanoid.cs
+++ b/Assets/MeshUtility/Runtime/Humanoid.cs
@@ -102,7 +102,7 @@ IEnumerable<Validation> Required(params (string, Transform)[] props)
         {
             foreach (var prop in props)
             {
-                if (prop.Item2 is null)
+                if (prop.Item2 == null)
                 {
                     var name = prop.Item1;
                     if (name.StartsWith("m_"))
@@ -406,12 +406,12 @@ public void AssignBones(IEnumerable<(HumanBodyBones, Transform)> nodes)
         public bool AssignBonesFromAnimator()
         {
             var animator = GetComponent<Animator>();
-            if (animator is null)
+            if (animator == null)
             {
                 return false;
             }
             var avatar = animator.avatar;
-            if (avatar is null)
+            if (avatar == null)
             {
                 return false;
             }
diff --git a/Assets/VRM/UniVRM/Editor/Format/VRMExporterWizard.cs b/Assets/VRM/UniVRM/Editor/Format/VRMExporterWizard.cs
index 97854aecd4..8036f16816 100644
--- a/Assets/VRM/UniVRM/Editor/Format/VRMExporterWizard.cs
+++ b/Assets/VRM/UniVRM/Editor/Format/VRMExporterWizard.cs
@@ -131,7 +131,7 @@ public static bool HasRotationOrScale(GameObject root)
 
         static Vector3 GetForward(Transform l, Transform r)
         {
-            if (l is null || r is null)
+            if (l == null || r == null)
             {
                 return Vector3.zero;
             }
@@ -322,7 +322,7 @@ static BeginVerticalScrollViewFunc BeginVerticalScrollView
         {
             get
             {
-                if (s_func is null)
+                if (s_func == null)
                 {
                     var methods = typeof(EditorGUILayout).GetMethods(BindingFlags.Static | BindingFlags.NonPublic).Where(x => x.Name == "BeginVerticalScrollView").ToArray();
                     var method = methods.First(x => x.GetParameters()[1].ParameterType == typeof(bool));