diff --git a/u01/node.h b/u01/node.h
index 6d15ef4..34db8e2 100644
--- a/u01/node.h
+++ b/u01/node.h
@@ -1,5 +1,5 @@
-#ifndef _NODE_H
-#define _NODE_H
+#pragma once
+
 #include <memory>
 #include <string>
 #include <vector>
@@ -21,4 +21,3 @@ private:
 };
 
 node *create_complete_tree(std::size_t nr_child_nodes, unsigned int tree_depth);
-#endif