diff --git a/cv4/list_ops.c b/cv4/list_ops.c
index ae8cfb3..3c524b3 100644
--- a/cv4/list_ops.c
+++ b/cv4/list_ops.c
@@ -7,7 +7,7 @@
 list_t *new_list(size_t length, list_element_t elements[]) {
     list_t *list = malloc(sizeof(list_t) + length * sizeof(list_element_t));
     list->length = length;
-    for (int i = 0; i < length; i++) {
+    for (size_t i = 0; i < length; i++) {
         list->elements[i] = elements[i];
     }
     return list;
@@ -25,14 +25,14 @@ list_t *append_list(list_t *list1, list_t *list2) {
 list_t *filter_list(list_t *list, bool (*predicate)(list_element_t)) {
    list_element_t filter[list->length];
    int counter = 0;
-   for(int i = 0; i < list->length;i++){
+   for(size_t i = 0; i < list->length;i++){
      if(predicate(list->elements[i])){
        filter[counter] = list->elements[i];
        counter++;
    	}
    }
    list_t *result = malloc(list->length);
-   for(int i = 0;i < list->length;i++)
+   for(size_t i = 0;i < list->length;i++)
    		result->elements[i] = filter[i];
    return result;
 }
@@ -42,7 +42,7 @@ size_t length_list(list_t *list) {
 }
 
 list_t *map_list(list_t *list, list_element_t (*mapper)(list_element_t)) {
-    for (int i = 0; i < list->length; i++) {
+    for (size_t i = 0; i < list->length; i++) {
         list->elements[i] = mapper(list->elements[i]);
     }
 
@@ -52,23 +52,23 @@ list_t *map_list(list_t *list, list_element_t (*mapper)(list_element_t)) {
 
 
 list_element_t foldl_list(list_t *list, list_element_t initial, list_element_t (*folder)(list_element_t, list_element_t)) {
-    list_element_t accumulator = initial;
+    list_element_t result = initial;
     
     for (size_t i = 0; i < list->length; i++) {
-        accumulator = folder(accumulator, list->elements[i]);
+        result = folder(accumulator, list->elements[i]);
     }
     
-    return accumulator;
+    return result;
 }
 
 list_element_t foldr_list(list_t *list, list_element_t initial, list_element_t (*folder)(list_element_t, list_element_t)) {
-    list_element_t accumulator = initial;
+    list_element_t result = initial;
     
     for (size_t i = list->length; i > 0; i--) {
-        accumulator = folder(list->elements[i - 1], accumulator);
+        result = folder(list->elements[i - 1], accumulator);
     }
     
-    return accumulator;
+    return result;
 }
 
 list_t *reverse_list(list_t *list) {