diff --git a/include/nn/util/util_BitArray.h b/include/nn/util/util_BitArray.h
index edaf1ec..4699509 100644
--- a/include/nn/util/util_BitArray.h
+++ b/include/nn/util/util_BitArray.h
@@ -37,10 +37,14 @@ class BitArray {
     };
 
     class iterator {
+    public:
         typedef difference_type difference_type;
         typedef reference reference;
         typedef pointer pointer;
+        typedef std::random_access_iterator_tag iterator_category;
+        typedef value_type value_type;
 
+    private:
         BitArray* m_pParent;
         difference_type m_Pos;
 
@@ -69,10 +73,14 @@ class BitArray {
     };
 
     class const_iterator {
+    public:
         typedef difference_type difference_type;
         typedef const_reference reference;
         typedef const_pointer pointer;
+        typedef std::random_access_iterator_tag iterator_category;
+        typedef value_type value_type;
 
+    private:
         const BitArray* m_pParent;
         difference_type m_Pos;
 
@@ -180,4 +188,4 @@ class BitArray {
     RawType* m_pBuf;
     size_type m_Len;
 };
-}  // namespace nn::util
\ No newline at end of file
+}  // namespace nn::util
diff --git a/include/nn/util/util_IntrusiveList.h b/include/nn/util/util_IntrusiveList.h
index a0d7b42..319f43a 100644
--- a/include/nn/util/util_IntrusiveList.h
+++ b/include/nn/util/util_IntrusiveList.h
@@ -72,6 +72,7 @@ class IntrusiveListImplementation {
         typedef difference_type difference_type;
         typedef value_type* pointer;
         typedef value_type& reference;
+        typedef std::bidirectional_iterator_tag iterator_category;
 
         const_iterator(pointer p) : m_Node(p) {}
 
@@ -92,8 +93,10 @@ class IntrusiveListImplementation {
     class iterator {
     public:
         typedef value_type value_type;
+        typedef difference_type difference_type;
         typedef value_type* pointer;
         typedef value_type& reference;
+        typedef std::bidirectional_iterator_tag iterator_category;
 
         iterator(pointer p) : m_Node(p) {}
 
@@ -197,12 +200,15 @@ class IntrusiveList {
     typedef std::reverse_iterator<iterator> reverse_iterator;
     typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
     typedef int size_type;
+    typedef int difference_type;
 
     class const_iterator {
     public:
         typedef T value_type;
+        typedef difference_type difference_type;
         typedef value_type* pointer;
         typedef value_type& reference;
+        typedef std::bidirectional_iterator_tag iterator_category;
 
         reference operator*() const;
         pointer operator->() const;
@@ -228,8 +234,10 @@ class IntrusiveList {
     class iterator {
     public:
         typedef T value_type;
+        typedef difference_type difference_type;
         typedef value_type* pointer;
         typedef value_type& reference;
+        typedef std::bidirectional_iterator_tag iterator_category;
 
         operator const_iterator() const {
             return static_cast<detail::IntrusiveListImplementation::const_iterator>(m_Iterator);