diff --git a/src/Memory/UniquePtrList.hpp b/src/Memory/UniquePtrList.hpp
index 3b23697..f1d21e0 100644
--- a/src/Memory/UniquePtrList.hpp
+++ b/src/Memory/UniquePtrList.hpp
@@ -30,7 +30,7 @@ namespace ArbUt {
             }
         }
 
-        inline BorrowedPtr<ValueT> At(size_t index) {
+        inline BorrowedPtr<ValueT> At(size_t index) const {
 #ifndef NO_ASSERT
             if (index >= _vector.size() || index < 0) {
                 std::stringstream ss;
@@ -56,7 +56,7 @@ namespace ArbUt {
         }
 
         inline void Append(ValueT* value) { _vector.push_back(value); }
-        inline BorrowedPtr<ValueT> operator[](size_t index) { return At(index); }
+        inline BorrowedPtr<ValueT> operator[] (size_t index) const { return At(index); }
 
         inline size_t Count() const { return _vector.size(); }