diff --git a/examples/gltfutil/texture_dumper.h b/examples/gltfutil/texture_dumper.h
index 274888b..809b43a 100644
--- a/examples/gltfutil/texture_dumper.h
+++ b/examples/gltfutil/texture_dumper.h
@@ -7,7 +7,7 @@
 namespace gltfutil {
 class texture_dumper {
  public:
-  enum class texture_output_format { png, bmp, tga };
+  enum class texture_output_format { png, bmp, tga, not_specified };
 
  private:
   const tinygltf::Model& model;