diff --git a/array_backed_list.c b/array_backed_list.c
index 66e53a2..49594ea 100644
--- a/array_backed_list.c
+++ b/array_backed_list.c
@@ -75,6 +75,7 @@ static void increase_buffer(IntList list, unsigned int additional_capacity) {
             new_buffer[i] = list->buffer[i];
          }
          
+         free_mem(list->buffer);
          list->buffer = new_buffer;
          list->capacity += additional_capacity;
       }