diff --git a/Assets/VRM/UniJSON/Editor/Tests/Json/JsonFormatterTest.cs b/Assets/VRM/UniJSON/Editor/Tests/Json/JsonFormatterTest.cs
index 19f8de786..d8fcc52bf 100644
--- a/Assets/VRM/UniJSON/Editor/Tests/Json/JsonFormatterTest.cs
+++ b/Assets/VRM/UniJSON/Editor/Tests/Json/JsonFormatterTest.cs
@@ -43,5 +43,16 @@ namespace UniJSON
                 Assert.True(json.GetStoreBytes().ToEnumerable().SequenceEqual(bytes));
             }
         }
+
+        [Test]
+        public void ReUseFormatter()
+        {
+            IFormatter f = new JsonFormatter();
+            f.Value(1);
+
+            f.Clear();
+            // fail
+            f.Value(2);
+        }
     }
 }
diff --git a/Assets/VRM/UniJSON/Scripts/FormatterExtensions.cs b/Assets/VRM/UniJSON/Scripts/FormatterExtensions.cs
index 85f464b5c..c934b5031 100644
--- a/Assets/VRM/UniJSON/Scripts/FormatterExtensions.cs
+++ b/Assets/VRM/UniJSON/Scripts/FormatterExtensions.cs
@@ -9,11 +9,6 @@ namespace UniJSON
 {
     public static partial class FormatterExtensions
     {
-        public static void Clear(this IFormatter f)
-        {
-            f.GetStore().Clear();
-        }
-
         public static ArraySegment<Byte> GetStoreBytes(this IFormatter f)
         {
             return f.GetStore().Bytes;
diff --git a/Assets/VRM/UniJSON/Scripts/IFormatter.cs b/Assets/VRM/UniJSON/Scripts/IFormatter.cs
index 3fe99953e..101cfdd40 100644
--- a/Assets/VRM/UniJSON/Scripts/IFormatter.cs
+++ b/Assets/VRM/UniJSON/Scripts/IFormatter.cs
@@ -6,6 +6,7 @@ namespace UniJSON
     public interface IFormatter
     {
         IStore GetStore();
+        void Clear();
 
         void BeginList(int n);
         void EndList();
diff --git a/Assets/VRM/UniJSON/Scripts/MsgPack/MsgPackFormatter.cs b/Assets/VRM/UniJSON/Scripts/MsgPack/MsgPackFormatter.cs
index eea676d69..47e4ff388 100644
--- a/Assets/VRM/UniJSON/Scripts/MsgPack/MsgPackFormatter.cs
+++ b/Assets/VRM/UniJSON/Scripts/MsgPack/MsgPackFormatter.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Text;
 
 
 namespace UniJSON
@@ -16,6 +15,11 @@ namespace UniJSON
         {
         }
 
+        public void Clear()
+        {
+            m_store.Clear();
+        }
+
 #if false
         public bool MsgPack_Ext(IList list)
         {