diff --git a/cv4/list_ops.c b/cv4/list_ops.c
index 3b8a817..260f755 100644
--- a/cv4/list_ops.c
+++ b/cv4/list_ops.c
@@ -16,15 +16,16 @@ list_t *new_list(size_t length, list_element_t elements[]) {
     return list;
 }
 
-list_t *append_list(list_t *list1, list_t *list2) {
-    if (!list1 || !list2)
-        return NULL;
-    list_t *list = new_list(list1->length + list2->length, NULL);
-    if (!list)
-        return NULL;
-    memcpy(list->elements, list1->elements, sizeof(list_element_t) * list1->length);
-    memcpy(list->elements + list1->length, list2->elements, sizeof(list_element_t) * list2->length);
-    return list;
+list_t *append_list(list_t *list1, list_t *list2)
+{
+    size_t length = list1->length + list2->length;
+    list_t *newlist = malloc(sizeof(list_t) + sizeof(list_element_t) * length);
+    newlist->length = length;
+    for (size_t i = 0; i < list1->length; i++)
+        newlist->elements[i] = list1->elements[i];
+    for (size_t i = list1->length; i < newlist->length; i++)
+        newlist->elements[i] = list2->elements[i - list1->length];
+    return newlist;
 }
 
 list_t *filter_list(list_t *list, bool (*predicate)(list_element_t)) {