diff --git a/Assets/VRM10/Runtime/Migration/Migration.cs b/Assets/VRM10/Runtime/Migration/Migration.cs
index 4965304f3..ded7b64fb 100644
--- a/Assets/VRM10/Runtime/Migration/Migration.cs
+++ b/Assets/VRM10/Runtime/Migration/Migration.cs
@@ -444,6 +444,12 @@ namespace UniVRM10
             Migration.CheckMeta(vrm0["meta"], vrm1.Meta);
             Migration.CheckHumanoid(vrm0["humanoid"], vrm1.Humanoid);
         }
+
+        public static void Check(ListTreeNode<JsonValue> vrm0, UniGLTF.Extensions.VRMC_springBone.VRMC_springBone vrm1)
+        {
+            var a = 0;
+            // Migration.CheckSpringBone(vrm0["secondaryAnimation"], vrm1.sp)
+        }
         #endregion
     }
 }
diff --git a/Assets/VRM10/Tests/MigrationTests.cs b/Assets/VRM10/Tests/MigrationTests.cs
index 41fe7c900..f0a0bbd6f 100644
--- a/Assets/VRM10/Tests/MigrationTests.cs
+++ b/Assets/VRM10/Tests/MigrationTests.cs
@@ -17,22 +17,6 @@ namespace UniVRM10
             }
         }
 
-        UniGLTF.Extensions.VRMC_vrm.VRMC_vrm GetVRMC_vrm(UniGLTF.glTFExtension extensions)
-        {
-            if (extensions is UniGLTF.glTFExtensionImport import)
-            {
-                foreach (var kv in import.ObjectItems())
-                {
-                    if (kv.Key.GetUtf8String() == UniGLTF.Extensions.VRMC_vrm.VRMC_vrm.ExtensionNameUtf8)
-                    {
-                        return UniGLTF.Extensions.VRMC_vrm.GltfDeserializer.Deserialize(kv.Value);
-                    }
-                }
-            }
-
-            return default;
-        }
-
         static ListTreeNode<JsonValue> GetVRM0(byte[] bytes)
         {
             var glb = UniGLTF.Glb.Parse(bytes);
@@ -40,6 +24,22 @@ namespace UniVRM10
             return json["extensions"]["VRM"];
         }
 
+        T GetExtension<T>(UniGLTF.glTFExtension extensions, UniJSON.Utf8String key, Func<ListTreeNode<JsonValue>, T> deserializer)
+        {
+            if (extensions is UniGLTF.glTFExtensionImport import)
+            {
+                foreach (var kv in import.ObjectItems())
+                {
+                    if (kv.Key.GetUtf8String() == key)
+                    {
+                        return deserializer(kv.Value);
+                    }
+                }
+            }
+
+            return default;
+        }
+
         [Test]
         public void Migrate0to1()
         {
@@ -50,10 +50,11 @@ namespace UniVRM10
             var glb = UniGLTF.Glb.Parse(vrm1);
             var json = glb.Json.Bytes.ParseAsJson();
             var gltf = UniGLTF.GltfDeserializer.Deserialize(json);
-            var VRMC_vrm = GetVRMC_vrm(gltf.extensions);
-            Assert.NotNull(VRMC_vrm);
 
-            Migration.Check(vrm0Json, VRMC_vrm);
+            Migration.Check(vrm0Json, GetExtension(gltf.extensions, UniGLTF.Extensions.VRMC_vrm.VRMC_vrm.ExtensionNameUtf8,
+                UniGLTF.Extensions.VRMC_vrm.GltfDeserializer.Deserialize));
+            Migration.Check(vrm0Json, GetExtension(gltf.extensions, UniGLTF.Extensions.VRMC_springBone.VRMC_springBone.ExtensionNameUtf8,
+                UniGLTF.Extensions.VRMC_springBone.GltfDeserializer.Deserialize));
         }
     }
 }