diff --git a/cache.go b/cache.go
index 845d945..08482b4 100644
--- a/cache.go
+++ b/cache.go
@@ -23,6 +23,11 @@ func (item *Item) Expired() bool {
 	return item.Expiration.Before(time.Now())
 }
 
+const (
+	NoExpiration      time.Duration = -1
+	DefaultExpiration time.Duration = 0
+)
+
 type Cache struct {
 	*cache
 	// If this is confusing, see the comment at the bottom of New()
@@ -35,9 +40,9 @@ type cache struct {
 	janitor           *janitor
 }
 
-// Add an item to the cache, replacing any existing item. If the duration is 0,
-// the cache's default expiration time is used. If it is -1, the item never
-// expires.
+// Add an item to the cache, replacing any existing item. If the duration is 0
+// (DefaultExpiration), the cache's default expiration time is used. If it is -1
+// (NoExpiration), the item never expires.
 func (c *cache) Set(k string, x interface{}, d time.Duration) {
 	c.Lock()
 	c.set(k, x, d)
@@ -48,7 +53,7 @@ func (c *cache) Set(k string, x interface{}, d time.Duration) {
 
 func (c *cache) set(k string, x interface{}, d time.Duration) {
 	var e *time.Time
-	if d == 0 {
+	if d == DefaultExpiration {
 		d = c.defaultExpiration
 	}
 	if d > 0 {
@@ -982,10 +987,10 @@ func newCacheWithJanitor(de time.Duration, ci time.Duration, m map[string]*Item)
 }
 
 // Return a new cache with a given default expiration duration and cleanup
-// interval. If the expiration duration is less than 1, the items in the cache
-// never expire (by default), and must be deleted manually. If the cleanup
-// interval is less than one, expired items are not deleted from the cache
-// before calling DeleteExpired.
+// interval. If the expiration duration is less than one (or NoExpiration),
+// the items in the cache never expire (by default), and must be deleted
+// manually. If the cleanup interval is less than one, expired items are not
+// deleted from the cache before calling DeleteExpired.
 func New(defaultExpiration, cleanupInterval time.Duration) *Cache {
 	items := make(map[string]*Item)
 	return newCacheWithJanitor(defaultExpiration, cleanupInterval, items)
diff --git a/cache_test.go b/cache_test.go
index 3e5d939..0bd8996 100644
--- a/cache_test.go
+++ b/cache_test.go
@@ -16,7 +16,7 @@ type TestStruct struct {
 }
 
 func TestCache(t *testing.T) {
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 
 	a, found := tc.Get("a")
 	if found || a != nil {
@@ -33,9 +33,9 @@ func TestCache(t *testing.T) {
 		t.Error("Getting C found value that shouldn't exist:", c)
 	}
 
-	tc.Set("a", 1, 0)
-	tc.Set("b", "b", 0)
-	tc.Set("c", 3.5, 0)
+	tc.Set("a", 1, DefaultExpiration)
+	tc.Set("b", "b", DefaultExpiration)
+	tc.Set("c", 3.5, DefaultExpiration)
 
 	x, found := tc.Get("a")
 	if !found {
@@ -72,8 +72,8 @@ func TestCacheTimes(t *testing.T) {
 	var found bool
 
 	tc := New(50*time.Millisecond, 1*time.Millisecond)
-	tc.Set("a", 1, 0)
-	tc.Set("b", 2, -1)
+	tc.Set("a", 1, DefaultExpiration)
+	tc.Set("b", 2, NoExpiration)
 	tc.Set("c", 3, 20*time.Millisecond)
 	tc.Set("d", 4, 70*time.Millisecond)
 
@@ -117,7 +117,7 @@ func TestNewFrom(t *testing.T) {
 			Expiration: nil,
 		},
 	}
-	tc := NewFrom(0, 0, m)
+	tc := NewFrom(DefaultExpiration, 0, m)
 	a, found := tc.Get("a")
 	if !found {
 		t.Fatal("Did not find a")
@@ -135,8 +135,8 @@ func TestNewFrom(t *testing.T) {
 }
 
 func TestStorePointerToStruct(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("foo", &TestStruct{Num: 1}, 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("foo", &TestStruct{Num: 1}, DefaultExpiration)
 	x, found := tc.Get("foo")
 	if !found {
 		t.Fatal("*TestStruct was not found for foo")
@@ -155,8 +155,8 @@ func TestStorePointerToStruct(t *testing.T) {
 }
 
 func TestIncrementWithInt(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint", 1, 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint", 1, DefaultExpiration)
 	err := tc.Increment("tint", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -171,8 +171,8 @@ func TestIncrementWithInt(t *testing.T) {
 }
 
 func TestIncrementWithInt8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint8", int8(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint8", int8(1), DefaultExpiration)
 	err := tc.Increment("tint8", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -187,8 +187,8 @@ func TestIncrementWithInt8(t *testing.T) {
 }
 
 func TestIncrementWithInt16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint16", int16(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint16", int16(1), DefaultExpiration)
 	err := tc.Increment("tint16", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -203,8 +203,8 @@ func TestIncrementWithInt16(t *testing.T) {
 }
 
 func TestIncrementWithInt32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint32", int32(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint32", int32(1), DefaultExpiration)
 	err := tc.Increment("tint32", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -219,8 +219,8 @@ func TestIncrementWithInt32(t *testing.T) {
 }
 
 func TestIncrementWithInt64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint64", int64(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint64", int64(1), DefaultExpiration)
 	err := tc.Increment("tint64", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -235,8 +235,8 @@ func TestIncrementWithInt64(t *testing.T) {
 }
 
 func TestIncrementWithUint(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint", uint(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint", uint(1), DefaultExpiration)
 	err := tc.Increment("tuint", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -251,8 +251,8 @@ func TestIncrementWithUint(t *testing.T) {
 }
 
 func TestIncrementWithUintptr(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuintptr", uintptr(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuintptr", uintptr(1), DefaultExpiration)
 	err := tc.Increment("tuintptr", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -268,8 +268,8 @@ func TestIncrementWithUintptr(t *testing.T) {
 }
 
 func TestIncrementWithUint8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint8", uint8(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint8", uint8(1), DefaultExpiration)
 	err := tc.Increment("tuint8", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -284,8 +284,8 @@ func TestIncrementWithUint8(t *testing.T) {
 }
 
 func TestIncrementWithUint16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint16", uint16(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint16", uint16(1), DefaultExpiration)
 	err := tc.Increment("tuint16", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -301,8 +301,8 @@ func TestIncrementWithUint16(t *testing.T) {
 }
 
 func TestIncrementWithUint32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint32", uint32(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint32", uint32(1), DefaultExpiration)
 	err := tc.Increment("tuint32", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -317,8 +317,8 @@ func TestIncrementWithUint32(t *testing.T) {
 }
 
 func TestIncrementWithUint64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint64", uint64(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint64", uint64(1), DefaultExpiration)
 	err := tc.Increment("tuint64", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -334,8 +334,8 @@ func TestIncrementWithUint64(t *testing.T) {
 }
 
 func TestIncrementWithFloat32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float32", float32(1.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float32", float32(1.5), DefaultExpiration)
 	err := tc.Increment("float32", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -350,8 +350,8 @@ func TestIncrementWithFloat32(t *testing.T) {
 }
 
 func TestIncrementWithFloat64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float64", float64(1.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float64", float64(1.5), DefaultExpiration)
 	err := tc.Increment("float64", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -366,8 +366,8 @@ func TestIncrementWithFloat64(t *testing.T) {
 }
 
 func TestIncrementFloatWithFloat32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float32", float32(1.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float32", float32(1.5), DefaultExpiration)
 	err := tc.IncrementFloat("float32", 2)
 	if err != nil {
 		t.Error("Error incrementfloating:", err)
@@ -382,8 +382,8 @@ func TestIncrementFloatWithFloat32(t *testing.T) {
 }
 
 func TestIncrementFloatWithFloat64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float64", float64(1.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float64", float64(1.5), DefaultExpiration)
 	err := tc.IncrementFloat("float64", 2)
 	if err != nil {
 		t.Error("Error incrementfloating:", err)
@@ -398,8 +398,8 @@ func TestIncrementFloatWithFloat64(t *testing.T) {
 }
 
 func TestDecrementWithInt(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int", int(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int", int(5), DefaultExpiration)
 	err := tc.Decrement("int", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -414,8 +414,8 @@ func TestDecrementWithInt(t *testing.T) {
 }
 
 func TestDecrementWithInt8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int8", int8(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int8", int8(5), DefaultExpiration)
 	err := tc.Decrement("int8", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -430,8 +430,8 @@ func TestDecrementWithInt8(t *testing.T) {
 }
 
 func TestDecrementWithInt16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int16", int16(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int16", int16(5), DefaultExpiration)
 	err := tc.Decrement("int16", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -446,8 +446,8 @@ func TestDecrementWithInt16(t *testing.T) {
 }
 
 func TestDecrementWithInt32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int32", int32(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int32", int32(5), DefaultExpiration)
 	err := tc.Decrement("int32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -462,8 +462,8 @@ func TestDecrementWithInt32(t *testing.T) {
 }
 
 func TestDecrementWithInt64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int64", int64(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int64", int64(5), DefaultExpiration)
 	err := tc.Decrement("int64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -478,8 +478,8 @@ func TestDecrementWithInt64(t *testing.T) {
 }
 
 func TestDecrementWithUint(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint", uint(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint", uint(5), DefaultExpiration)
 	err := tc.Decrement("uint", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -494,8 +494,8 @@ func TestDecrementWithUint(t *testing.T) {
 }
 
 func TestDecrementWithUintptr(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uintptr", uintptr(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uintptr", uintptr(5), DefaultExpiration)
 	err := tc.Decrement("uintptr", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -510,8 +510,8 @@ func TestDecrementWithUintptr(t *testing.T) {
 }
 
 func TestDecrementWithUint8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint8", uint8(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint8", uint8(5), DefaultExpiration)
 	err := tc.Decrement("uint8", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -526,8 +526,8 @@ func TestDecrementWithUint8(t *testing.T) {
 }
 
 func TestDecrementWithUint16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint16", uint16(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint16", uint16(5), DefaultExpiration)
 	err := tc.Decrement("uint16", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -542,8 +542,8 @@ func TestDecrementWithUint16(t *testing.T) {
 }
 
 func TestDecrementWithUint32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint32", uint32(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint32", uint32(5), DefaultExpiration)
 	err := tc.Decrement("uint32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -558,8 +558,8 @@ func TestDecrementWithUint32(t *testing.T) {
 }
 
 func TestDecrementWithUint64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint64", uint64(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint64", uint64(5), DefaultExpiration)
 	err := tc.Decrement("uint64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -574,8 +574,8 @@ func TestDecrementWithUint64(t *testing.T) {
 }
 
 func TestDecrementWithFloat32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float32", float32(5.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float32", float32(5.5), DefaultExpiration)
 	err := tc.Decrement("float32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -590,8 +590,8 @@ func TestDecrementWithFloat32(t *testing.T) {
 }
 
 func TestDecrementWithFloat64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float64", float64(5.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float64", float64(5.5), DefaultExpiration)
 	err := tc.Decrement("float64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -606,8 +606,8 @@ func TestDecrementWithFloat64(t *testing.T) {
 }
 
 func TestDecrementFloatWithFloat32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float32", float32(5.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float32", float32(5.5), DefaultExpiration)
 	err := tc.DecrementFloat("float32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -622,8 +622,8 @@ func TestDecrementFloatWithFloat32(t *testing.T) {
 }
 
 func TestDecrementFloatWithFloat64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float64", float64(5.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float64", float64(5.5), DefaultExpiration)
 	err := tc.DecrementFloat("float64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -638,8 +638,8 @@ func TestDecrementFloatWithFloat64(t *testing.T) {
 }
 
 func TestIncrementInt(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint", 1, 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint", 1, DefaultExpiration)
 	n, err := tc.IncrementInt("tint", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -657,8 +657,8 @@ func TestIncrementInt(t *testing.T) {
 }
 
 func TestIncrementInt8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint8", int8(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint8", int8(1), DefaultExpiration)
 	n, err := tc.IncrementInt8("tint8", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -676,8 +676,8 @@ func TestIncrementInt8(t *testing.T) {
 }
 
 func TestIncrementInt16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint16", int16(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint16", int16(1), DefaultExpiration)
 	n, err := tc.IncrementInt16("tint16", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -695,8 +695,8 @@ func TestIncrementInt16(t *testing.T) {
 }
 
 func TestIncrementInt32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint32", int32(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint32", int32(1), DefaultExpiration)
 	n, err := tc.IncrementInt32("tint32", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -714,8 +714,8 @@ func TestIncrementInt32(t *testing.T) {
 }
 
 func TestIncrementInt64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tint64", int64(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tint64", int64(1), DefaultExpiration)
 	n, err := tc.IncrementInt64("tint64", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -733,8 +733,8 @@ func TestIncrementInt64(t *testing.T) {
 }
 
 func TestIncrementUint(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint", uint(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint", uint(1), DefaultExpiration)
 	n, err := tc.IncrementUint("tuint", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -752,8 +752,8 @@ func TestIncrementUint(t *testing.T) {
 }
 
 func TestIncrementUintptr(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuintptr", uintptr(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuintptr", uintptr(1), DefaultExpiration)
 	n, err := tc.IncrementUintptr("tuintptr", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -771,8 +771,8 @@ func TestIncrementUintptr(t *testing.T) {
 }
 
 func TestIncrementUint8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint8", uint8(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint8", uint8(1), DefaultExpiration)
 	n, err := tc.IncrementUint8("tuint8", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -790,8 +790,8 @@ func TestIncrementUint8(t *testing.T) {
 }
 
 func TestIncrementUint16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint16", uint16(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint16", uint16(1), DefaultExpiration)
 	n, err := tc.IncrementUint16("tuint16", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -809,8 +809,8 @@ func TestIncrementUint16(t *testing.T) {
 }
 
 func TestIncrementUint32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint32", uint32(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint32", uint32(1), DefaultExpiration)
 	n, err := tc.IncrementUint32("tuint32", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -828,8 +828,8 @@ func TestIncrementUint32(t *testing.T) {
 }
 
 func TestIncrementUint64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("tuint64", uint64(1), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("tuint64", uint64(1), DefaultExpiration)
 	n, err := tc.IncrementUint64("tuint64", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -847,8 +847,8 @@ func TestIncrementUint64(t *testing.T) {
 }
 
 func TestIncrementFloat32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float32", float32(1.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float32", float32(1.5), DefaultExpiration)
 	n, err := tc.IncrementFloat32("float32", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -866,8 +866,8 @@ func TestIncrementFloat32(t *testing.T) {
 }
 
 func TestIncrementFloat64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float64", float64(1.5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float64", float64(1.5), DefaultExpiration)
 	n, err := tc.IncrementFloat64("float64", 2)
 	if err != nil {
 		t.Error("Error incrementing:", err)
@@ -885,8 +885,8 @@ func TestIncrementFloat64(t *testing.T) {
 }
 
 func TestDecrementInt8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int8", int8(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int8", int8(5), DefaultExpiration)
 	n, err := tc.DecrementInt8("int8", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -904,8 +904,8 @@ func TestDecrementInt8(t *testing.T) {
 }
 
 func TestDecrementInt16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int16", int16(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int16", int16(5), DefaultExpiration)
 	n, err := tc.DecrementInt16("int16", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -923,8 +923,8 @@ func TestDecrementInt16(t *testing.T) {
 }
 
 func TestDecrementInt32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int32", int32(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int32", int32(5), DefaultExpiration)
 	n, err := tc.DecrementInt32("int32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -942,8 +942,8 @@ func TestDecrementInt32(t *testing.T) {
 }
 
 func TestDecrementInt64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int64", int64(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int64", int64(5), DefaultExpiration)
 	n, err := tc.DecrementInt64("int64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -961,8 +961,8 @@ func TestDecrementInt64(t *testing.T) {
 }
 
 func TestDecrementUint(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint", uint(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint", uint(5), DefaultExpiration)
 	n, err := tc.DecrementUint("uint", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -980,8 +980,8 @@ func TestDecrementUint(t *testing.T) {
 }
 
 func TestDecrementUintptr(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uintptr", uintptr(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uintptr", uintptr(5), DefaultExpiration)
 	n, err := tc.DecrementUintptr("uintptr", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -999,8 +999,8 @@ func TestDecrementUintptr(t *testing.T) {
 }
 
 func TestDecrementUint8(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint8", uint8(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint8", uint8(5), DefaultExpiration)
 	n, err := tc.DecrementUint8("uint8", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -1018,8 +1018,8 @@ func TestDecrementUint8(t *testing.T) {
 }
 
 func TestDecrementUint16(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint16", uint16(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint16", uint16(5), DefaultExpiration)
 	n, err := tc.DecrementUint16("uint16", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -1037,8 +1037,8 @@ func TestDecrementUint16(t *testing.T) {
 }
 
 func TestDecrementUint32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint32", uint32(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint32", uint32(5), DefaultExpiration)
 	n, err := tc.DecrementUint32("uint32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -1056,8 +1056,8 @@ func TestDecrementUint32(t *testing.T) {
 }
 
 func TestDecrementUint64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint64", uint64(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint64", uint64(5), DefaultExpiration)
 	n, err := tc.DecrementUint64("uint64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -1075,8 +1075,8 @@ func TestDecrementUint64(t *testing.T) {
 }
 
 func TestDecrementFloat32(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float32", float32(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float32", float32(5), DefaultExpiration)
 	n, err := tc.DecrementFloat32("float32", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -1094,8 +1094,8 @@ func TestDecrementFloat32(t *testing.T) {
 }
 
 func TestDecrementFloat64(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("float64", float64(5), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("float64", float64(5), DefaultExpiration)
 	n, err := tc.DecrementFloat64("float64", 2)
 	if err != nil {
 		t.Error("Error decrementing:", err)
@@ -1113,33 +1113,33 @@ func TestDecrementFloat64(t *testing.T) {
 }
 
 func TestAdd(t *testing.T) {
-	tc := New(0, 0)
-	err := tc.Add("foo", "bar", 0)
+	tc := New(DefaultExpiration, 0)
+	err := tc.Add("foo", "bar", DefaultExpiration)
 	if err != nil {
 		t.Error("Couldn't add foo even though it shouldn't exist")
 	}
-	err = tc.Add("foo", "baz", 0)
+	err = tc.Add("foo", "baz", DefaultExpiration)
 	if err == nil {
 		t.Error("Successfully added another foo when it should have returned an error")
 	}
 }
 
 func TestReplace(t *testing.T) {
-	tc := New(0, 0)
-	err := tc.Replace("foo", "bar", 0)
+	tc := New(DefaultExpiration, 0)
+	err := tc.Replace("foo", "bar", DefaultExpiration)
 	if err == nil {
 		t.Error("Replaced foo when it shouldn't exist")
 	}
-	tc.Set("foo", "bar", 0)
-	err = tc.Replace("foo", "bar", 0)
+	tc.Set("foo", "bar", DefaultExpiration)
+	err = tc.Replace("foo", "bar", DefaultExpiration)
 	if err != nil {
 		t.Error("Couldn't replace existing key foo")
 	}
 }
 
 func TestDelete(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("foo", "bar", 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("foo", "bar", DefaultExpiration)
 	tc.Delete("foo")
 	x, found := tc.Get("foo")
 	if found {
@@ -1151,19 +1151,19 @@ func TestDelete(t *testing.T) {
 }
 
 func TestItemCount(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("foo", "1", 0)
-	tc.Set("bar", "2", 0)
-	tc.Set("baz", "3", 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("foo", "1", DefaultExpiration)
+	tc.Set("bar", "2", DefaultExpiration)
+	tc.Set("baz", "3", DefaultExpiration)
 	if n := tc.ItemCount(); n != 3 {
 		t.Errorf("Item count is not 3: %d", n)
 	}
 }
 
 func TestFlush(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("foo", "bar", 0)
-	tc.Set("baz", "yes", 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("foo", "bar", DefaultExpiration)
+	tc.Set("baz", "yes", DefaultExpiration)
 	tc.Flush()
 	x, found := tc.Get("foo")
 	if found {
@@ -1182,8 +1182,8 @@ func TestFlush(t *testing.T) {
 }
 
 func TestIncrementOverflowInt(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("int8", int8(127), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("int8", int8(127), DefaultExpiration)
 	err := tc.Increment("int8", 1)
 	if err != nil {
 		t.Error("Error incrementing int8:", err)
@@ -1197,8 +1197,8 @@ func TestIncrementOverflowInt(t *testing.T) {
 }
 
 func TestIncrementOverflowUint(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint8", uint8(255), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint8", uint8(255), DefaultExpiration)
 	err := tc.Increment("uint8", 1)
 	if err != nil {
 		t.Error("Error incrementing int8:", err)
@@ -1211,8 +1211,8 @@ func TestIncrementOverflowUint(t *testing.T) {
 }
 
 func TestDecrementUnderflowUint(t *testing.T) {
-	tc := New(0, 0)
-	tc.Set("uint8", uint8(0), 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("uint8", uint8(0), DefaultExpiration)
 	err := tc.Decrement("uint8", 1)
 	if err != nil {
 		t.Error("Error decrementing int8:", err)
@@ -1225,7 +1225,7 @@ func TestDecrementUnderflowUint(t *testing.T) {
 }
 
 func TestCacheSerialization(t *testing.T) {
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 	testFillAndSerialize(t, tc)
 
 	// Check if gob.Register behaves properly even after multiple gob.Register
@@ -1234,26 +1234,26 @@ func TestCacheSerialization(t *testing.T) {
 }
 
 func testFillAndSerialize(t *testing.T, tc *Cache) {
-	tc.Set("a", "a", 0)
-	tc.Set("b", "b", 0)
-	tc.Set("c", "c", 0)
+	tc.Set("a", "a", DefaultExpiration)
+	tc.Set("b", "b", DefaultExpiration)
+	tc.Set("c", "c", DefaultExpiration)
 	tc.Set("expired", "foo", 1*time.Millisecond)
-	tc.Set("*struct", &TestStruct{Num: 1}, 0)
+	tc.Set("*struct", &TestStruct{Num: 1}, DefaultExpiration)
 	tc.Set("[]struct", []TestStruct{
 		{Num: 2},
 		{Num: 3},
-	}, 0)
+	}, DefaultExpiration)
 	tc.Set("[]*struct", []*TestStruct{
 		&TestStruct{Num: 4},
 		&TestStruct{Num: 5},
-	}, 0)
+	}, DefaultExpiration)
 	tc.Set("structception", &TestStruct{
 		Num: 42,
 		Children: []*TestStruct{
 			&TestStruct{Num: 6174},
 			&TestStruct{Num: 4716},
 		},
-	}, 0)
+	}, DefaultExpiration)
 
 	fp := &bytes.Buffer{}
 	err := tc.Save(fp)
@@ -1261,7 +1261,7 @@ func testFillAndSerialize(t *testing.T, tc *Cache) {
 		t.Fatal("Couldn't save cache to fp:", err)
 	}
 
-	oc := New(0, 0)
+	oc := New(DefaultExpiration, 0)
 	err = oc.Load(fp)
 	if err != nil {
 		t.Fatal("Couldn't load cache from fp:", err)
@@ -1352,9 +1352,9 @@ func testFillAndSerialize(t *testing.T, tc *Cache) {
 }
 
 func TestFileSerialization(t *testing.T) {
-	tc := New(0, 0)
-	tc.Add("a", "a", 0)
-	tc.Add("b", "b", 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Add("a", "a", DefaultExpiration)
+	tc.Add("b", "b", DefaultExpiration)
 	f, err := ioutil.TempFile("", "go-cache-cache.dat")
 	if err != nil {
 		t.Fatal("Couldn't create cache file:", err)
@@ -1363,7 +1363,7 @@ func TestFileSerialization(t *testing.T) {
 	f.Close()
 	tc.SaveFile(fname)
 
-	oc := New(0, 0)
+	oc := New(DefaultExpiration, 0)
 	oc.Add("a", "aa", 0) // this should not be overwritten
 	err = oc.LoadFile(fname)
 	if err != nil {
@@ -1391,10 +1391,10 @@ func TestFileSerialization(t *testing.T) {
 }
 
 func TestSerializeUnserializable(t *testing.T) {
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 	ch := make(chan bool, 1)
 	ch <- true
-	tc.Set("chan", ch, 0)
+	tc.Set("chan", ch, DefaultExpiration)
 	fp := &bytes.Buffer{}
 	err := tc.Save(fp) // this should fail gracefully
 	if err.Error() != "gob NewTypeObject can't handle type: chan bool" {
@@ -1404,8 +1404,8 @@ func TestSerializeUnserializable(t *testing.T) {
 
 func BenchmarkCacheGet(b *testing.B) {
 	b.StopTimer()
-	tc := New(0, 0)
-	tc.Set("foo", "bar", 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("foo", "bar", DefaultExpiration)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.Get("foo")
@@ -1428,8 +1428,8 @@ func BenchmarkRWMutexMapGet(b *testing.B) {
 
 func BenchmarkCacheGetConcurrent(b *testing.B) {
 	b.StopTimer()
-	tc := New(0, 0)
-	tc.Set("foo", "bar", 0)
+	tc := New(DefaultExpiration, 0)
+	tc.Set("foo", "bar", DefaultExpiration)
 	wg := new(sync.WaitGroup)
 	workers := runtime.NumCPU()
 	each := b.N / workers
@@ -1475,12 +1475,12 @@ func BenchmarkCacheGetManyConcurrent(b *testing.B) {
 	// can be compared against BenchmarkShardedCacheGetManyConcurrent.
 	b.StopTimer()
 	n := 10000
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 	keys := make([]string, n)
 	for i := 0; i < n; i++ {
 		k := "foo" + strconv.Itoa(n)
 		keys[i] = k
-		tc.Set(k, "bar", 0)
+		tc.Set(k, "bar", DefaultExpiration)
 	}
 	each := b.N / n
 	wg := new(sync.WaitGroup)
@@ -1500,12 +1500,12 @@ func BenchmarkCacheGetManyConcurrent(b *testing.B) {
 func BenchmarkShardedCacheGetManyConcurrent(b *testing.B) {
 	b.StopTimer()
 	n := 10000
-	tsc := unexportedNewSharded(20, 0, 0)
+	tsc := unexportedNewSharded(20, DefaultExpiration, 0)
 	keys := make([]string, n)
 	for i := 0; i < n; i++ {
 		k := "foo" + strconv.Itoa(n)
 		keys[i] = k
-		tsc.Set(k, "bar", 0)
+		tsc.Set(k, "bar", DefaultExpiration)
 	}
 	each := b.N / n
 	wg := new(sync.WaitGroup)
@@ -1524,10 +1524,10 @@ func BenchmarkShardedCacheGetManyConcurrent(b *testing.B) {
 
 func BenchmarkCacheSet(b *testing.B) {
 	b.StopTimer()
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
-		tc.Set("foo", "bar", 0)
+		tc.Set("foo", "bar", DefaultExpiration)
 	}
 }
 
@@ -1545,10 +1545,10 @@ func BenchmarkRWMutexMapSet(b *testing.B) {
 
 func BenchmarkCacheSetDelete(b *testing.B) {
 	b.StopTimer()
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
-		tc.Set("foo", "bar", 0)
+		tc.Set("foo", "bar", DefaultExpiration)
 		tc.Delete("foo")
 	}
 }
@@ -1570,11 +1570,11 @@ func BenchmarkRWMutexMapSetDelete(b *testing.B) {
 
 func BenchmarkCacheSetDeleteSingleLock(b *testing.B) {
 	b.StopTimer()
-	tc := New(0, 0)
+	tc := New(DefaultExpiration, 0)
 	b.StartTimer()
 	for i := 0; i < b.N; i++ {
 		tc.Lock()
-		tc.set("foo", "bar", 0)
+		tc.set("foo", "bar", DefaultExpiration)
 		tc.delete("foo")
 		tc.Unlock()
 	}