diff --git a/list/list.h b/list/list.h
index 38c9203..9b069db 100644
--- a/list/list.h
+++ b/list/list.h
@@ -1,15 +1,15 @@
 typedef struct Node{
-	unsigned long int id;//what's this?
+	unsigned long int id;
 	void *value;
-	Node *next;
-	Node *last;
-};
+	struct Node *next;
+	struct Node *last;
+}Node;
 
 typedef struct List{
 	Node *head;
 	Node *tail;
 	unsigned long int length;
-};
+}List;
 
 List *init_list();
 Node *init_node();
@@ -29,6 +29,7 @@ int insertInHead(List *p_list, Node *p_node){
 	//p_node->last = NULL;
 	p_node->next = p_list->head;
 	p_list->head = p_node;
+	return 0;
 }
 
 int insertInTail(List *p_list, Node *p_node){
@@ -36,4 +37,5 @@ int insertInTail(List *p_list, Node *p_node){
 	//p_node->next = NULL;
 	p_node->last = p_list->tail;
 	p_list->tail = p_node;
+	return 0;
 }