diff --git a/README.md b/README.md
index 4a4b9b8..34ddda8 100644
--- a/README.md
+++ b/README.md
@@ -24,16 +24,14 @@ type myMap = Map[string,int] // the equal sign here is critical!
 type myStdMap = StdMap[string, int]
 
 func main() {
-	m := new(Map[string, int])
-	
-	m.Copy(myStdMap{"b":2, "c":3})
-	m.Set("a",1)
-
-	sum := 0
-	for v := range m.All() {
-		sum += v
-    }
-	fmt.Print(sum)
+  m := new(Map[string, int])
+  m.Copy(myStdMap{"b":2, "c":3})
+  m.Set("a",1)
+  sum := 0
+  for v := range m.All() {
+    sum += v
+  }
+  fmt.Print(sum)
 }
 
 ```
diff --git a/set.go b/set.go
index a4b2a83..c806899 100644
--- a/set.go
+++ b/set.go
@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"iter"
-	"slices"
 )
 
 // Set is a collection that keeps track of membership.
@@ -168,9 +167,8 @@ func (m *Set[K]) UnmarshalJSON(in []byte) (err error) {
 
 // String returns the set as a string.
 func (m *Set[K]) String() string {
-	vals := slices.Clone(m.Values())
 	ret := "{"
-	for i, v := range vals {
+	for i, v := range m.Values() {
 		ret += fmt.Sprintf("%#v", v)
 		if i < m.Len()-1 {
 			ret += ","
diff --git a/set_ordered.go b/set_ordered.go
index 5ce05af..f91c5ec 100644
--- a/set_ordered.go
+++ b/set_ordered.go
@@ -58,3 +58,18 @@ func (m *OrderedSet[K]) All() iter.Seq[K] {
 	v := m.Values()
 	return slices.Values(v)
 }
+
+// Clone returns a copy of the Set. This is a shallow clone:
+// the new keys and values are set using ordinary assignment.
+func (m *OrderedSet[K]) Clone() *OrderedSet[K] {
+	m1 := NewOrderedSet[K]()
+	m1.items = m.items.Clone()
+	return m1
+}
+
+// Add adds the value to the set.
+// If the value already exists, nothing changes.
+func (m *OrderedSet[K]) Add(k ...K) SetI[K] {
+	m.Set.Add(k...)
+	return m
+}
diff --git a/set_ordered_test.go b/set_ordered_test.go
index 2e69d0b..d45fde9 100644
--- a/set_ordered_test.go
+++ b/set_ordered_test.go
@@ -101,3 +101,12 @@ func TestOrderedSet_Range(t *testing.T) {
 		})
 	}
 }
+
+func TestOrderedSet_Clone(t *testing.T) {
+	m1 := NewOrderedSet("a", "b", "c")
+	m2 := m1.Clone()
+	assert.True(t, m1.Equal(m2))
+
+	m2.Add("d")
+	assert.False(t, m1.Equal(m2))
+}
diff --git a/seti.go b/seti.go
index f5db475..b3f834c 100644
--- a/seti.go
+++ b/seti.go
@@ -15,6 +15,5 @@ type SetI[K comparable] interface {
 	Delete(k K)
 	All() iter.Seq[K]
 	Insert(seq iter.Seq[K])
-	Clone() *Set[K]
 	DeleteFunc(del func(K) bool)
 }