diff --git a/safe_map_test.go b/safe_map_test.go
index 7890853..ac39fb7 100644
--- a/safe_map_test.go
+++ b/safe_map_test.go
@@ -16,7 +16,7 @@ func init() {
 	gob.Register(new(SafeMap[string, int]))
 }
 
-func TestNil(t *testing.T) {
+func TestSafeMap_Nil(t *testing.T) {
 	var m SafeMap[string, int]
 
 	assert.False(t, m.Has("z"))
diff --git a/set.go b/set.go
index c806899..84779a2 100644
--- a/set.go
+++ b/set.go
@@ -32,11 +32,17 @@ func NewSet[K comparable](values ...K) *Set[K] {
 
 // Clear resets the set to an empty set
 func (m *Set[K]) Clear() {
+	if m == nil {
+		return
+	}
 	m.items = nil
 }
 
 // Len returns the number of items in the set
 func (m *Set[K]) Len() int {
+	if m == nil || m.items == nil {
+		return 0
+	}
 	return m.items.Len()
 }
 
@@ -45,7 +51,7 @@ func (m *Set[K]) Len() int {
 // While its safe to call methods of the set from within the Range function, its discouraged.
 // If you ever switch to one of the SafeSet sets, it will cause a deadlock.
 func (m *Set[K]) Range(f func(k K) bool) {
-	if m == nil || m.items == nil {
+	if m.Len() == 0 {
 		return
 	}
 	for k := range m.items {
@@ -57,22 +63,34 @@ func (m *Set[K]) Range(f func(k K) bool) {
 
 // Has returns true if the value exists in the set.
 func (m *Set[K]) Has(k K) bool {
+	if m.Len() == 0 {
+		return false
+	}
 	return m.items.Has(k)
 }
 
 // Delete removes the value from the set. If the value does not exist, nothing happens.
 func (m *Set[K]) Delete(k K) {
+	if m.Len() == 0 {
+		return
+	}
 	m.items.Delete(k)
 }
 
 // Values returns a new slice containing the values of the set.
 func (m *Set[K]) Values() []K {
+	if m.Len() == 0 {
+		return nil
+	}
 	return m.items.Keys()
 }
 
 // Add adds the value to the set.
 // If the value already exists, nothing changes.
 func (m *Set[K]) Add(k ...K) SetI[K] {
+	if m == nil {
+		panic("cannot add values to a nil Set")
+	}
 	if m.items == nil {
 		m.items = make(map[K]struct{})
 	}
@@ -90,6 +108,9 @@ func (m *Set[K]) Merge(in SetI[K]) {
 
 // Copy adds the values from in to the set.
 func (m *Set[K]) Copy(in SetI[K]) {
+	if m == nil {
+		panic("cannot copy to a nil Set")
+	}
 	if in == nil || in.Len() == 0 {
 		return
 	}
@@ -104,6 +125,9 @@ func (m *Set[K]) Copy(in SetI[K]) {
 
 // Equal returns true if the two sets are the same length and contain the same values.
 func (m *Set[K]) Equal(m2 SetI[K]) bool {
+	if m == nil {
+		return m2.Len() == 0
+	}
 	if m.Len() != m2.Len() {
 		return false
 	}
@@ -168,10 +192,12 @@ func (m *Set[K]) UnmarshalJSON(in []byte) (err error) {
 // String returns the set as a string.
 func (m *Set[K]) String() string {
 	ret := "{"
-	for i, v := range m.Values() {
-		ret += fmt.Sprintf("%#v", v)
-		if i < m.Len()-1 {
-			ret += ","
+	if m.Len() != 0 {
+		for i, v := range m.Values() {
+			ret += fmt.Sprintf("%#v", v)
+			if i < m.Len()-1 {
+				ret += ","
+			}
 		}
 	}
 	ret += "}"
@@ -180,12 +206,20 @@ func (m *Set[K]) String() string {
 
 // All returns an iterator over all the items in the set. Order is not determinate.
 func (m *Set[K]) All() iter.Seq[K] {
+	if m.Len() == 0 {
+		return func(yield func(K) bool) {
+			return
+		}
+	}
 	return m.items.KeysIter()
 }
 
 // Insert adds the values from seq to the map.
 // Duplicates are overridden.
 func (m *Set[K]) Insert(seq iter.Seq[K]) {
+	if m == nil {
+		panic("cannot insert into a nil Set")
+	}
 	if m.items == nil {
 		m.items = NewStdMap[K, struct{}]()
 	}
@@ -207,12 +241,17 @@ func CollectSet[K comparable](seq iter.Seq[K]) *Set[K] {
 // the new keys and values are set using ordinary assignment.
 func (m *Set[K]) Clone() *Set[K] {
 	m1 := NewSet[K]()
-	m1.items = m.items.Clone()
+	if m.Len() != 0 {
+		m1.items = m.items.Clone()
+	}
 	return m1
 }
 
 // DeleteFunc deletes any values for which del returns true.
 func (m *Set[K]) DeleteFunc(del func(K) bool) {
+	if m.Len() == 0 {
+		return
+	}
 	del2 := func(k K, s struct{}) bool {
 		return del(k)
 	}
diff --git a/set_ordered.go b/set_ordered.go
index f91c5ec..2902952 100644
--- a/set_ordered.go
+++ b/set_ordered.go
@@ -3,6 +3,7 @@ package maps
 import (
 	"cmp"
 	"encoding/json"
+	"fmt"
 	"iter"
 	"slices"
 )
@@ -25,9 +26,25 @@ func NewOrderedSet[K cmp.Ordered](values ...K) *OrderedSet[K] {
 	return s
 }
 
+// Clear resets the set to an empty set
+func (m *OrderedSet[K]) Clear() {
+	if m == nil {
+		return
+	}
+	m.Set.Clear()
+}
+
+// Len returns the number of items in the set
+func (m *OrderedSet[K]) Len() int {
+	if m == nil || m.items == nil {
+		return 0
+	}
+	return m.Set.Len()
+}
+
 // Range will range over the values in order.
 func (m *OrderedSet[K]) Range(f func(k K) bool) {
-	if m == nil || m.items == nil {
+	if m.Len() == 0 {
 		return
 	}
 	values := m.Values()
@@ -38,13 +55,58 @@ func (m *OrderedSet[K]) Range(f func(k K) bool) {
 	}
 }
 
-// Values returns the values as a slice, in order.
+// Has returns true if the value exists in the set.
+func (m *OrderedSet[K]) Has(k K) bool {
+	if m.Len() == 0 {
+		return false
+	}
+	return m.Set.Has(k)
+}
+
+// Delete removes the value from the set. If the value does not exist, nothing happens.
+func (m *OrderedSet[K]) Delete(k K) {
+	if m.Len() == 0 {
+		return
+	}
+	m.Set.Delete(k)
+}
+
+// Equal returns true if the two sets are the same length and contain the same values.
+func (m *OrderedSet[K]) Equal(m2 SetI[K]) bool {
+	if m == nil {
+		return m2.Len() == 0
+	}
+	return m.Set.Equal(m2)
+}
+
+// Values returns a new slice containing the values of the set.
 func (m *OrderedSet[K]) Values() []K {
+	if m.Len() == 0 {
+		return nil
+	}
 	v := m.items.Keys()
 	slices.Sort(v)
 	return v
 }
 
+// Add adds the value to the set.
+// If the value already exists, nothing changes.
+func (m *OrderedSet[K]) Add(k ...K) SetI[K] {
+	if m == nil {
+		panic("cannot add values to a nil Set")
+	}
+	m.Set.Add(k...)
+	return m
+}
+
+// Copy adds the values from in to the set.
+func (m *OrderedSet[K]) Copy(in SetI[K]) {
+	if m == nil {
+		panic("cannot copy to a nil Set")
+	}
+	m.Set.Copy(in)
+}
+
 // MarshalJSON implements the json.Marshaler interface to convert the map into a JSON object.
 func (m *OrderedSet[K]) MarshalJSON() (out []byte, err error) {
 	if m.Len() == 0 {
@@ -55,21 +117,56 @@ func (m *OrderedSet[K]) MarshalJSON() (out []byte, err error) {
 
 // All returns an iterator over all the items in the set. Order is determinate.
 func (m *OrderedSet[K]) All() iter.Seq[K] {
+	if m.Len() == 0 {
+		return func(yield func(K) bool) {
+			return
+		}
+	}
 	v := m.Values()
 	return slices.Values(v)
 }
 
+// Insert adds the values from seq to the map.
+// Duplicates are overridden.
+func (m *OrderedSet[K]) Insert(seq iter.Seq[K]) {
+	if m == nil {
+		panic("cannot insert into a nil Set")
+	}
+	m.Set.Insert(seq)
+}
+
 // 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()
+	if m != nil {
+		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
+// DeleteFunc deletes any values for which del returns true.
+func (m *OrderedSet[K]) DeleteFunc(del func(K) bool) {
+	if m.Len() == 0 {
+		return
+	}
+	m.Set.DeleteFunc(del)
+}
+
+// String returns the set as a string.
+func (m *OrderedSet[K]) String() string {
+	if m == nil {
+		return "{}"
+	}
+	ret := "{"
+	if m.Len() != 0 {
+		for i, v := range m.Values() {
+			ret += fmt.Sprintf("%#v", v)
+			if i < m.Len()-1 {
+				ret += ","
+			}
+		}
+	}
+	ret += "}"
+	return ret
 }
diff --git a/set_ordered_test.go b/set_ordered_test.go
index d45fde9..fab1235 100644
--- a/set_ordered_test.go
+++ b/set_ordered_test.go
@@ -3,7 +3,9 @@ package maps
 import (
 	"cmp"
 	"encoding/gob"
+	"fmt"
 	"github.com/stretchr/testify/assert"
+	"slices"
 	"testing"
 )
 
@@ -11,11 +13,11 @@ type orderedSetT = OrderedSet[string]
 type orderedSetTI = SetI[string]
 
 func TestOrderedSet_SetI(t *testing.T) {
-	runSetITests[OrderedSet[string]](t, makeSetI[OrderedSet[string]])
+	runSetITests[orderedSetT](t, makeSetI[orderedSetT])
 }
 
 func init() {
-	gob.Register(new(OrderedSet[string]))
+	gob.Register(new(orderedSetT))
 }
 
 func TestOrderedSet_Values(t *testing.T) {
@@ -58,7 +60,7 @@ func TestOrderedSet_MarshalJSON(t *testing.T) {
 	}
 }
 
-func TestOrderedSetAll(t *testing.T) {
+func TestOrderedSet_All(t *testing.T) {
 	set := NewOrderedSet[int]()
 	set.Add(5)
 	set.Add(3)
@@ -107,6 +109,54 @@ func TestOrderedSet_Clone(t *testing.T) {
 	m2 := m1.Clone()
 	assert.True(t, m1.Equal(m2))
 
+	var m3 *OrderedSet[string]
+	m4 := m3.Clone()
+	m3.Equal(m4)
+	assert.True(t, m3.Equal(m4))
+
 	m2.Add("d")
 	assert.False(t, m1.Equal(m2))
 }
+
+func TestOrderedSet_Nil(t *testing.T) {
+	t.Run("Nil", func(t *testing.T) {
+		var m1, m2 *OrderedSet[string]
+
+		assert.Equal(t, 0, m1.Len())
+		m1.Clear()
+		assert.True(t, m1.Equal(m2))
+		m3 := m2.Clone()
+		assert.True(t, m1.Equal(m3))
+		m3.Add("a")
+		assert.False(t, m1.Equal(m3))
+		m1.Range(func(k string) bool {
+			assert.Fail(t, "no range should happen")
+			return false
+		})
+		assert.False(t, m1.Has("b"))
+		m1.Delete("a")
+		assert.Empty(t, m1.Values())
+		assert.Equal(t, "{}", m1.String())
+		m1.DeleteFunc(func(k string) bool {
+			return false
+		})
+		for _ = range m1.All() {
+			assert.Fail(t, "no range should happen")
+		}
+		assert.Panics(t, func() {
+			m1.Insert(slices.Values([]string{"a"}))
+		})
+		assert.Panics(t, func() {
+			m1.Add("a")
+		})
+		assert.Panics(t, func() {
+			m1.Copy(m2)
+		})
+	})
+}
+
+func ExampleOrderedSet_String() {
+	m := NewOrderedSet("a", "c", "a", "b")
+	fmt.Print(m.String())
+	// Output: {"a","b","c"}
+}
diff --git a/set_test.go b/set_test.go
index a787c1a..4113b97 100644
--- a/set_test.go
+++ b/set_test.go
@@ -4,7 +4,7 @@ import (
 	"encoding/gob"
 	"fmt"
 	"github.com/stretchr/testify/assert"
-	"sort"
+	"slices"
 	"testing"
 )
 
@@ -22,12 +22,8 @@ func init() {
 func ExampleSet_String() {
 	m := new(Set[string])
 	m.Add("a")
-	m.Add("b")
-	m.Add("a")
-	v := m.Values()
-	sort.Strings(v)
-	fmt.Print(v)
-	// Output: [a b]
+	fmt.Print(m.String())
+	// Output: {"a"}
 }
 
 func TestCollectSet(t *testing.T) {
@@ -43,3 +39,42 @@ func TestSet_Clone(t *testing.T) {
 	m3 := m2.Clone()
 	assert.True(t, m1.Equal(m3))
 }
+
+func TestSet_Nil(t *testing.T) {
+	t.Run("Nil", func(t *testing.T) {
+		var m1, m2 *Set[string]
+
+		assert.Equal(t, 0, m1.Len())
+		m1.Clear()
+		assert.True(t, m1.Equal(m2))
+		m3 := m2.Clone()
+		assert.True(t, m1.Equal(m3))
+		m3.Add("a")
+		assert.False(t, m1.Equal(m3))
+		m1.Range(func(k string) bool {
+			assert.Fail(t, "no range should happen")
+			return false
+		})
+		assert.False(t, m1.Has("b"))
+		m1.Delete("a")
+		assert.Empty(t, m1.Values())
+		assert.Equal(t, "{}", m1.String())
+		m1.DeleteFunc(func(k string) bool {
+			return false
+		})
+
+		for _ = range m1.All() {
+			assert.Fail(t, "no range should happen")
+		}
+		assert.Panics(t, func() {
+			m1.Insert(slices.Values([]string{"a"}))
+		})
+		assert.Panics(t, func() {
+			m1.Add("a")
+		})
+		assert.Panics(t, func() {
+			m1.Copy(m2)
+		})
+
+	})
+}
diff --git a/seti.go b/seti.go
index b3f834c..15547df 100644
--- a/seti.go
+++ b/seti.go
@@ -7,6 +7,7 @@ type SetI[K comparable] interface {
 	Add(k ...K) SetI[K]
 	Clear()
 	Len() int
+	Copy(in SetI[K])
 	Range(func(k K) bool)
 	Has(k K) bool
 	Values() []K
diff --git a/seti_test.go b/seti_test.go
index 1c5e898..75469e3 100644
--- a/seti_test.go
+++ b/seti_test.go
@@ -37,6 +37,7 @@ func runSetITests[M any](t *testing.T, f makeSetF) {
 	testSetAll(t, f)
 	testSetInsert(t, f)
 	testSetDeleteFunc(t, f)
+	testSetCopy(t, f)
 }
 
 func testSetClear(t *testing.T, f makeSetF) {
@@ -201,8 +202,7 @@ func testSetMarshalJSON(t *testing.T, f makeSetF) {
 		s, err = json.Marshal(m)
 		assert.NoError(t, err)
 		// Note: The below output is what is produced, but isn't guaranteed. go seems to currently be sorting keys
-		assert.Equal(t, string(s), "[]")
-
+		assert.Equal(t, "[]", string(s))
 	})
 }
 
@@ -286,3 +286,12 @@ func testSetDeleteFunc(t *testing.T, f makeSetF) {
 		assert.Equal(t, 1, m1.Len())
 	})
 }
+
+func testSetCopy(t *testing.T, f makeSetF) {
+	t.Run("DeleteFunc", func(t *testing.T) {
+		m1 := f("a", "b", "c")
+		m2 := f()
+		m2.Copy(m1)
+		assert.True(t, m1.Equal(m2))
+	})
+}