1 files changed, 2 insertions, 1 deletions

diff --git a/src/sp_list.c b/src/sp_list.c
index c798d6d..0f00371 100644
--- a/src/sp_list.c
+++ b/src/sp_list.c
@@ -10,7 +10,8 @@ void sp_list_free(sp_list_node *node) {
 
 // Thanks to https://en.wikipedia.org/wiki/Insertion_sort :>
 sp_list_node *sp_list_sort(sp_list_node *pList,
-                           int (*cmp_func)(sp_list_node *, sp_list_node *)) {
+                           int (*cmp_func)(sp_list_node const *const,
+                                           sp_list_node const *const)) {
   sp_list_node *head = NULL;
 
   if (pList == NULL || pList->next == NULL) {