diff --git a/vector/data/one/code.cpp b/vector/data/one/code.cpp
index 4360888..8aa982d 100644
--- a/vector/data/one/code.cpp
+++ b/vector/data/one/code.cpp
@@ -95,8 +95,11 @@ void TestInsert()
 	for (int i = 0; i < 10; ++i) {
 		v.push_back(i);
 	}
+  std::cerr<<"Now back is"<< v.back()<<std::endl;
 	v.insert(v.begin() + 3, 100);
+  std::cerr<<"Now back is"<< v.back()<<std::endl;
 	v.insert(v.begin() + 5, 200);
+  std::cerr<<"Now back is"<< v.back()<<std::endl;
 	for (sjtu::vector<int>::iterator it = v.begin(); it != v.end(); ++it) {
 		std::cout << *it << " ";
 	}
diff --git a/vector/src/vector.hpp b/vector/src/vector.hpp
index 769aaf7..fbc7ac3 100644
--- a/vector/src/vector.hpp
+++ b/vector/src/vector.hpp
@@ -368,7 +368,7 @@ class vector {
       raw_end = raw_beg + current_length;
       allocated_length = new_allocated_length;
     }
-    for (T *i = raw_end - 1; i != pos.raw_pointer; --i) {
+    for (T *i = raw_end; i != pos.raw_pointer; --i) {
       std::allocator_traits<decltype(alloc)>::construct(alloc, i, std::move(*(i - 1)));
       std::allocator_traits<decltype(alloc)>::destroy(alloc, i - 1);
     }
@@ -398,7 +398,7 @@ class vector {
       raw_end = raw_beg + current_length;
       allocated_length = new_allocated_length;
     }
-    for (T *i = raw_end - 1; i != raw_beg + ind; --i) {
+    for (T *i = raw_end; i != raw_beg + ind; --i) {
       alloc.construct(i, std::move(*(i - 1)));
       alloc.destroy(i - 1);
     }