diff --git a/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java b/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
index 63fca40229..aaecfa9912 100644
--- a/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
+++ b/src/test/java/org/apache/commons/collections4/CollectionUtilsTest.java
@@ -596,7 +596,7 @@ public void testCollate() {
 
         final List<Integer> combinedList = new ArrayList<>(collectionD);
         combinedList.addAll(collectionE);
-        combinedList.sort(null);
+        Collections.sort(combinedList);
 
         assertEquals(combinedList, result2, "Merge two lists 2");
 
@@ -640,7 +640,7 @@ public void testCollateIgnoreDuplicates() {
         final Set<Integer> combinedSet = new HashSet<>(collectionD);
         combinedSet.addAll(collectionE);
         final List<Integer> combinedList = new ArrayList<>(combinedSet);
-        combinedList.sort(null);
+        Collections.sort(combinedList);
 
         assertEquals(combinedList, result2, "Merge two lists 2 - ignore duplicates");
     }