diff -r 3ee5a5c7823a -r 313fd460d264 src/linked_list.c
--- a/src/linked_list.c	Sun Nov 30 15:06:02 2025 +0100
+++ b/src/linked_list.c	Sun Nov 30 15:41:15 2025 +0100
@@ -692,8 +692,13 @@
 }
 
 static void *cx_ll_malloc_node(const cx_linked_list *list) {
-    return cxZalloc(list->base.collection.allocator,
-                    list->loc_data + list->base.collection.elem_size + list->extra_data_len);
+    size_t n;
+    if (list->extra_data_len == 0) {
+        n = list->loc_data + list->base.collection.elem_size;
+    } else {
+        n = list->loc_extra + list->extra_data_len;
+    }
+    return cxZalloc(list->base.collection.allocator, n);
 }
 
 static int cx_ll_insert_at(
@@ -1267,12 +1272,22 @@
 
     cx_linked_list *list = cxCalloc(allocator, 1, sizeof(cx_linked_list));
     if (list == NULL) return NULL;
-    list->extra_data_len = 0;
     list->loc_prev = 0;
     list->loc_next = sizeof(void*);
     list->loc_data = sizeof(void*)*2;
+    list->loc_extra = -1;
+    list->extra_data_len = 0;
     cx_list_init((CxList*)list, &cx_linked_list_class,
             allocator, comparator, elem_size);
 
     return (CxList *) list;
 }
+
+void cx_linked_list_extra_data(cx_linked_list *list, size_t len) {
+    list->extra_data_len = len;
+
+    off_t loc_extra = list->loc_data + list->base.collection.elem_size;
+    size_t alignment = alignof(void*);
+    size_t padding = alignment - (loc_extra % alignment);
+    list->loc_extra = loc_extra + padding;
+}