diff --git a/Scripts/SkinnedMeshUtility/BoneMeshEraser.cs b/Scripts/SkinnedMeshUtility/BoneMeshEraser.cs
index da7afbef8..72578d34a 100644
--- a/Scripts/SkinnedMeshUtility/BoneMeshEraser.cs
+++ b/Scripts/SkinnedMeshUtility/BoneMeshEraser.cs
@@ -71,6 +71,10 @@ namespace VRM
             var mesh = new Mesh();
             mesh.name = src.name + "(erased)";
 
+#if UNITY_2017_3_OR_NEWER
+            mesh.indexFormat = src.indexFormat;
+#endif
+
             mesh.vertices = src.vertices;
             mesh.normals = src.normals;
             mesh.uv = src.uv;
diff --git a/Scripts/SkinnedMeshUtility/Editor/BoneNormalizer.cs b/Scripts/SkinnedMeshUtility/Editor/BoneNormalizer.cs
index 0cb3645d5..685c05ec6 100644
--- a/Scripts/SkinnedMeshUtility/Editor/BoneNormalizer.cs
+++ b/Scripts/SkinnedMeshUtility/Editor/BoneNormalizer.cs
@@ -145,6 +145,10 @@ namespace VRM
 
                         var mesh = new Mesh();
                         mesh.name = srcMesh.name + ".baked";
+#if UNITY_2017_3_OR_NEWER
+                        mesh.indexFormat = srcMesh.indexFormat;
+#endif
+
                         srcRenderer.BakeMesh(mesh);
 
                         //var m = src.localToWorldMatrix;