diff --git a/README.md b/README.md
index 8a375e5..6754c99 100644
--- a/README.md
+++ b/README.md
@@ -1 +1 @@
-My solutions to some [exercism](https://exercism.io/) exercises.
+My solutions to some [exercism](https://exercism.org/) exercises.
diff --git a/c/linked-list/linked_list.c b/c/linked-list/linked_list.c
index 977109c..1f42e91 100644
--- a/c/linked-list/linked_list.c
+++ b/c/linked-list/linked_list.c
@@ -1,8 +1,20 @@
 #include <malloc.h>
 
-#include "br-list.h"
+#include "list.h"
 #include "linked_list.h"
 
+/* How it works :
+ *
+ * The usual way to use linked lists is to have a list_head whith
+ * 'next' pointing to first node, and 'prev' pointing to last node.
+ * Each node has also 'prev' and 'next' pointers.
+ *
+ * Here, list_head points to  the node own list_head structure,
+ * and each node list_head points to next/previous node list_head.
+ *
+ * Advantage: We don't need to manipulate the pointers, all lists
+ * use the same code, independently of the object (node) structure.
+ */
 struct list_node {
     ll_data_t data;
     struct list_head list;
@@ -40,7 +52,7 @@ size_t list_count(const struct list *list_head)
 
 /* inserts item at back of a list
  */
-void list_push(struct list *list, ll_data_t item_data)
+void list_push(const struct list *list, const ll_data_t item_data)
 {
     struct list_node *p;
 
@@ -52,7 +64,7 @@ void list_push(struct list *list, ll_data_t item_data)
 
 /* deletes an element
  */
-static ll_data_t _list_del(struct list_head *list)
+static ll_data_t _list_del(const struct list_head *list)
 {
     struct list_node *node;
     ll_data_t data;
@@ -66,14 +78,14 @@ static ll_data_t _list_del(struct list_head *list)
 
 /* removes item from back of a list
  */
-ll_data_t list_pop(struct list *list)
+ll_data_t list_pop(const struct list *list)
 {
     return list_empty((struct list_head*)list) ? -1 : _list_del(list->prev);
 }
 
 /* inserts item at front of a list
  */
-void list_unshift(struct list *list, ll_data_t item_data)
+void list_unshift(const struct list *list, const ll_data_t item_data)
 {
     struct list_node *p;
 
@@ -85,14 +97,14 @@ void list_unshift(struct list *list, ll_data_t item_data)
 
 /* removes item from front of a list
  */
-ll_data_t list_shift(struct list *list)
+ll_data_t list_shift(const struct list *list)
 {
     return list_empty((struct list_head*)list) ? -1 : _list_del(list->next);
 }
 
 /* finds a element that matches data
  */
-static struct list_node *_node_find(struct list *list, ll_data_t data)
+static struct list_node *_node_find(const struct list *list, const ll_data_t data)
 {
     struct list_node *p;
 
@@ -105,7 +117,7 @@ static struct list_node *_node_find(struct list *list, ll_data_t data)
 
 /* deletes a node that holds the matching data
  */
-void list_delete(struct list *list, ll_data_t data)
+void list_delete(const struct list *list, const ll_data_t data)
 {
     struct list_node *p;
 
@@ -118,7 +130,8 @@ void list_delete(struct list *list, ll_data_t data)
  */
 void list_destroy(struct list *list)
 {
-    struct list_head *cur, *tmp;
+    struct list_head *cur;
+    __typeof(cur) tmp;
 
     list_for_each_safe(cur, tmp, (struct list_head *)list)
         _list_del(cur);
diff --git a/c/linked-list/linked_list.h b/c/linked-list/linked_list.h
index b524caf..5e10abb 100644
--- a/c/linked-list/linked_list.h
+++ b/c/linked-list/linked_list.h
@@ -13,19 +13,19 @@ struct list *list_create(void);
 size_t list_count(const struct list *list);
 
 // inserts item at back of a list
-void list_push(struct list *list, ll_data_t item_data);
+void list_push(const struct list *list, const ll_data_t item_data);
 
 // removes item from back of a list
-ll_data_t list_pop(struct list *list);
+ll_data_t list_pop(const struct list *list);
 
 // inserts item at front of a list
-void list_unshift(struct list *list, ll_data_t item_data);
+void list_unshift(const struct list *list, const ll_data_t item_data);
 
 // removes item from front of a list
-ll_data_t list_shift(struct list *list);
+ll_data_t list_shift(const struct list *list);
 
 // deletes a node that holds the matching data
-void list_delete(struct list *list, ll_data_t data);
+void list_delete(const struct list *list, const ll_data_t data);
 
 // destroys an entire list
 // list will be a dangling pointer after calling this method on it
diff --git a/c/linked-list/br-list.h b/c/linked-list/list.h
similarity index 100%
rename from c/linked-list/br-list.h
rename to c/linked-list/list.h