diff --git a/classpath/java/util/Collections.java b/classpath/java/util/Collections.java
index bbc4e60b3f..d4b295fd58 100644
--- a/classpath/java/util/Collections.java
+++ b/classpath/java/util/Collections.java
@@ -3,10 +3,10 @@ package java.util;
 public class Collections {
   private Collections() { }
 
-  static String toString(List l) {
+  static String toString(Collection c) {
     StringBuilder sb = new StringBuilder();
     sb.append("[");
-    for (Iterator it = l.iterator(); it.hasNext();) {
+    for (Iterator it = c.iterator(); it.hasNext();) {
       sb.append(it.next());
       if (it.hasNext()) {
         sb.append(",");
diff --git a/classpath/java/util/TreeSet.java b/classpath/java/util/TreeSet.java
index 47343c65d3..dbebe04fbc 100644
--- a/classpath/java/util/TreeSet.java
+++ b/classpath/java/util/TreeSet.java
@@ -17,6 +17,10 @@ public class TreeSet<T> implements Collection<T> {
     return new MyIterator<T>(set.first());
   }
 
+  public String toString() {
+    return Collections.toString(this);
+  }
+
   public boolean add(T value) {
     PersistentSet.Path<Cell<T>> p = set.find(new Cell(value, null));
     if (p.fresh()) {