diff --git a/TinySTL/Algorithm.h b/TinySTL/Algorithm.h
index 567eea5..c5610cc 100644
--- a/TinySTL/Algorithm.h
+++ b/TinySTL/Algorithm.h
@@ -446,11 +446,19 @@ namespace TinySTL{
 	namespace {
 		template<class InputIterator, class Distance>
 		void _advance(InputIterator& it, Distance n, input_iterator_tag){
+			assert(n >= 0);
+			while (n--){
+				++it;
+			}
+		}
+		template<class BidirectionIterator, class Distance>
+		void _advance(BidirectionIterator& it, Distance n, bidirectional_iterator_tag){
 			if (n < 0){
 				while (n++){
 					--it;
 				}
-			}else{
+			}
+			else{
 				while (n--){
 					++it;
 				}
diff --git a/TinySTL/Test/AlgorithmTest.cpp b/TinySTL/Test/AlgorithmTest.cpp
index 9bdd899..79b6afd 100644
--- a/TinySTL/Test/AlgorithmTest.cpp
+++ b/TinySTL/Test/AlgorithmTest.cpp
@@ -170,16 +170,20 @@ namespace TinySTL{
 		void testAdvance(){
 			TinySTL::vector<int> v;
 			TinySTL::list<int> l;
+			TinySTL::binary_search_tree<int> bst;
 			for (auto i = 0; i != 10; ++i){
 				v.push_back(i);
 				l.push_back(i);
+				bst.insert(i);
 			}
 			auto vit = v.begin();
 			auto lit = l.begin();
+			auto bit = bst.cbegin();
 
 			TinySTL::advance(vit, 5);
 			TinySTL::advance(lit, 5);
-			assert(*vit == 5 && *lit == 5);
+			TinySTL::advance(bit, 5);
+			assert(*vit == 5 && *lit == 5 && *bit == 5);
 
 			TinySTL::advance(vit, -5);
 			TinySTL::advance(lit, -5);
diff --git a/TinySTL/Test/AlgorithmTest.h b/TinySTL/Test/AlgorithmTest.h
index 775acd0..33c13a7 100644
--- a/TinySTL/Test/AlgorithmTest.h
+++ b/TinySTL/Test/AlgorithmTest.h
@@ -13,6 +13,7 @@
 #include <list>
 #include <vector>
 
+#include "../BinarySearchTree.h"
 #include "../List.h"
 #include "../Vector.h"