diff --git a/lib/base/dynamictype.h b/lib/base/dynamictype.h
index 13312c804..42456ac16 100644
--- a/lib/base/dynamictype.h
+++ b/lib/base/dynamictype.h
@@ -99,10 +99,21 @@ private:
 	int m_Index;
 	mutable shared_ptr<T> m_Current;
 
-	void increment(void) {
+	void increment(void)
+	{
 		m_Index++;
 	}
 
+	void decrement(void)
+	{
+		m_Index--;
+	}
+
+	void advance(int n)
+	{
+		m_Index += n;
+	}
+
 	bool equal(const DynamicTypeIterator<T>& other) const
 	{
 		ASSERT(other.m_Type == m_Type);