diff -r 5653a9626cc0 -r 0b8692959d37 src/ucx/list.c
--- a/src/ucx/list.c	Fri Jul 24 08:00:11 2020 +0200
+++ b/src/ucx/list.c	Tue Aug 25 12:07:56 2020 +0200
@@ -1,7 +1,7 @@
 /*
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
  *
- * Copyright 2016 Olaf Wintermann. All rights reserved.
+ * Copyright 2017 Mike Becker, Olaf Wintermann All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -26,7 +26,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "list.h"
+#include "ucx/list.h"
 
 UcxList *ucx_list_clone(UcxList *l, copy_func fnc, void *data) {
     return ucx_list_clone_a(ucx_default_allocator(), l, fnc, data);
@@ -77,6 +77,7 @@
 }
 
 void ucx_list_free_content(UcxList* list, ucx_destructor destr) {
+    if (!destr) destr = free;
     while (list != NULL) {
         destr(list->data);
         list = list->next;
@@ -205,15 +206,15 @@
     return s;
 }
 
-static UcxList *ucx_list_sort_merge(int length,
-        UcxList* restrict ls, UcxList* restrict le, UcxList* restrict re,
+static UcxList *ucx_list_sort_merge(size_t length,
+        UcxList* ls, UcxList* le, UcxList* re,
         cmp_func fnc, void* data) {
 
     UcxList** sorted = (UcxList**) malloc(sizeof(UcxList*)*length);
     UcxList *rc, *lc;
 
     lc = ls; rc = le;
-    int n = 0;
+    size_t n = 0;
     while (lc && lc != le && rc != re) {
         if (fnc(lc->data, rc->data, data) <= 0) {
             sorted[n] = lc;
@@ -254,9 +255,9 @@
     }
 
     UcxList *lc;
-    int ln = 1;
+    size_t ln = 1;
 
-    UcxList *restrict ls = l, *restrict le, *restrict re;
+    UcxList *ls = l, *le, *re;
     
     // check how many elements are already sorted
     lc = ls;
@@ -270,7 +271,7 @@
         return l; // this list is already sorted :)
     } else {
         UcxList *rc;
-        int rn = 1;
+        size_t rn = 1;
         rc = le;
         // skip already sorted elements
         while (rc->next != NULL && fnc(rc->next->data, rc->data, data) > 0) {