diff --git a/data_structure/doubly_linked_list.cpp b/data_structure/doubly_linked_list.cpp
index f8d4d83a2..17ea2983a 100644
--- a/data_structure/doubly_linked_list.cpp
+++ b/data_structure/doubly_linked_list.cpp
@@ -11,7 +11,7 @@ struct node {
 class double_linked_list {
  public:
   double_linked_list() {
-   start = NULL;
+    start = NULL;
   }
   void insert(int x);
   void remove(int x);