diff --git a/du6/list_ops.c b/du6/list_ops.c
index 209143a..6cd3e6b 100644
--- a/du6/list_ops.c
+++ b/du6/list_ops.c
@@ -82,7 +82,7 @@ list_element_t foldl_list(list_t *list, list_element_t initial,
 list_element_t foldr_list(list_t *list, list_element_t initial,
                           list_element_t (*foldr)(list_element_t, list_element_t)) {
     list_element_t result = initial;
-    for (ssize_t i = list->length - 1; i >= 0; i--) {
+    for (int i = (int)list->length - 1; i >= 0; i--) {
         result = foldr(list->elements[i], result);
     }
     return result;