diff --git a/toonz/sources/include/tcg/hash.h b/toonz/sources/include/tcg/hash.h
index c668090..78770e9 100644
--- a/toonz/sources/include/tcg/hash.h
+++ b/toonz/sources/include/tcg/hash.h
@@ -21,6 +21,11 @@ public:
   typedef T value_type;
   typedef Hash_functor hash_type;
 
+  struct BucketNode;
+  typedef typename tcg::list<BucketNode>::size_t size_t;
+  typedef typename tcg::list<BucketNode>::iterator iterator;
+  typedef typename tcg::list<BucketNode>::const_iterator const_iterator;
+
   struct BucketNode {
     K m_key;
     T m_val;
@@ -34,11 +39,6 @@ public:
     ~BucketNode() {}
   };
 
-  typedef typename tcg::list<BucketNode>::size_t size_t;
-
-  typedef typename tcg::list<BucketNode>::iterator iterator;
-  typedef typename tcg::list<BucketNode>::const_iterator const_iterator;
-
 private:
   std::vector<size_t> m_bucketsIdx;
   tcg::list<BucketNode> m_items;