diff --git a/cluster_test.go b/cluster_test.go
index 803338c..ce583ad 100644
--- a/cluster_test.go
+++ b/cluster_test.go
@@ -167,7 +167,7 @@ var _ = Describe("Cluster", func() {
 			Expect(err).To(Equal(redis.Nil))
 			Expect(val).To(Equal(""))
 
-			val, err = client.Set("A", "VALUE").Result()
+			val, err = client.Set("A", "VALUE", 0).Result()
 			Expect(err).NotTo(HaveOccurred())
 			Expect(val).To(Equal("OK"))
 
@@ -181,7 +181,7 @@ var _ = Describe("Cluster", func() {
 		})
 
 		It("should follow redirects", func() {
-			Expect(client.Set("A", "VALUE").Err()).NotTo(HaveOccurred())
+			Expect(client.Set("A", "VALUE", 0).Err()).NotTo(HaveOccurred())
 			Expect(redis.HashSlot("A")).To(Equal(6373))
 
 			// Slot 6373 is stored on the second node
diff --git a/command.go b/command.go
index a4bfcf8..977a313 100644
--- a/command.go
+++ b/command.go
@@ -338,12 +338,25 @@ func (cmd *BoolCmd) String() string {
 
 func (cmd *BoolCmd) parseReply(rd *bufio.Reader) error {
 	v, err := parseReply(rd, nil)
+	// `SET key value NX` returns nil when key already exists.
+	if err == Nil {
+		cmd.val = false
+		return nil
+	}
 	if err != nil {
 		cmd.err = err
 		return err
 	}
-	cmd.val = v.(int64) == 1
-	return nil
+	switch vv := v.(type) {
+	case int64:
+		cmd.val = vv == 1
+		return nil
+	case string:
+		cmd.val = vv == "OK"
+		return nil
+	default:
+		return fmt.Errorf("got %T, wanted int64 or string")
+	}
 }
 
 //------------------------------------------------------------------------------
diff --git a/command_test.go b/command_test.go
index c58528f..a02847e 100644
--- a/command_test.go
+++ b/command_test.go
@@ -26,7 +26,7 @@ var _ = Describe("Command", func() {
 	})
 
 	It("should have a plain string result", func() {
-		set := client.Set("foo", "bar")
+		set := client.Set("foo", "bar", 0)
 		Expect(set.String()).To(Equal("SET foo bar: OK"))
 
 		get := client.Get("foo")
@@ -34,7 +34,7 @@ var _ = Describe("Command", func() {
 	})
 
 	It("should have correct val/err states", func() {
-		set := client.Set("key", "hello")
+		set := client.Set("key", "hello", 0)
 		Expect(set.Err()).NotTo(HaveOccurred())
 		Expect(set.Val()).To(Equal("OK"))
 
@@ -47,7 +47,7 @@ var _ = Describe("Command", func() {
 	})
 
 	It("should escape special chars", func() {
-		set := client.Set("key", "hello1\r\nhello2\r\n")
+		set := client.Set("key", "hello1\r\nhello2\r\n", 0)
 		Expect(set.Err()).NotTo(HaveOccurred())
 		Expect(set.Val()).To(Equal("OK"))
 
@@ -58,7 +58,7 @@ var _ = Describe("Command", func() {
 
 	It("should handle big vals", func() {
 		val := string(bytes.Repeat([]byte{'*'}, 1<<16))
-		set := client.Set("key", val)
+		set := client.Set("key", val, 0)
 		Expect(set.Err()).NotTo(HaveOccurred())
 		Expect(set.Val()).To(Equal("OK"))
 
@@ -70,7 +70,7 @@ var _ = Describe("Command", func() {
 	It("should handle many keys #1", func() {
 		const n = 100000
 		for i := 0; i < n; i++ {
-			client.Set("keys.key"+strconv.Itoa(i), "hello"+strconv.Itoa(i))
+			client.Set("keys.key"+strconv.Itoa(i), "hello"+strconv.Itoa(i), 0)
 		}
 		keys := client.Keys("keys.*")
 		Expect(keys.Err()).NotTo(HaveOccurred())
@@ -83,7 +83,7 @@ var _ = Describe("Command", func() {
 		keys := []string{"non-existent-key"}
 		for i := 0; i < n; i++ {
 			key := "keys.key" + strconv.Itoa(i)
-			client.Set(key, "hello"+strconv.Itoa(i))
+			client.Set(key, "hello"+strconv.Itoa(i), 0)
 			keys = append(keys, key)
 		}
 		keys = append(keys, "non-existent-key")
@@ -100,7 +100,7 @@ var _ = Describe("Command", func() {
 	})
 
 	It("should convert strings via helpers", func() {
-		set := client.Set("key", "10")
+		set := client.Set("key", "10", 0)
 		Expect(set.Err()).NotTo(HaveOccurred())
 
 		n, err := client.Get("key").Int64()
diff --git a/commands.go b/commands.go
index f2a22e9..5154b79 100644
--- a/commands.go
+++ b/commands.go
@@ -25,6 +25,18 @@ func (c *commandable) Process(cmd Cmder) {
 	c.process(cmd)
 }
 
+func usePrecise(dur time.Duration) bool {
+	return dur < time.Second || dur%time.Second != 0
+}
+
+func formatMs(dur time.Duration) string {
+	return strconv.FormatInt(int64(dur/time.Millisecond), 10)
+}
+
+func formatSec(dur time.Duration) string {
+	return strconv.FormatInt(int64(dur/time.Second), 10)
+}
+
 //------------------------------------------------------------------------------
 
 func (c *commandable) Auth(password string) *StatusCmd {
@@ -77,8 +89,8 @@ func (c *commandable) Exists(key string) *BoolCmd {
 	return cmd
 }
 
-func (c *commandable) Expire(key string, dur time.Duration) *BoolCmd {
-	cmd := NewBoolCmd("EXPIRE", key, strconv.FormatInt(int64(dur/time.Second), 10))
+func (c *commandable) Expire(key string, expiration time.Duration) *BoolCmd {
+	cmd := NewBoolCmd("EXPIRE", key, formatSec(expiration))
 	c.Process(cmd)
 	return cmd
 }
@@ -146,8 +158,8 @@ func (c *commandable) Persist(key string) *BoolCmd {
 	return cmd
 }
 
-func (c *commandable) PExpire(key string, dur time.Duration) *BoolCmd {
-	cmd := NewBoolCmd("PEXPIRE", key, strconv.FormatInt(int64(dur/time.Millisecond), 10))
+func (c *commandable) PExpire(key string, expiration time.Duration) *BoolCmd {
+	cmd := NewBoolCmd("PEXPIRE", key, formatMs(expiration))
 	c.Process(cmd)
 	return cmd
 }
@@ -425,19 +437,22 @@ func (c *commandable) MSetNX(pairs ...string) *BoolCmd {
 	return cmd
 }
 
-func (c *commandable) PSetEx(key string, dur time.Duration, value string) *StatusCmd {
-	cmd := NewStatusCmd(
-		"PSETEX",
-		key,
-		strconv.FormatInt(int64(dur/time.Millisecond), 10),
-		value,
-	)
+func (c *commandable) PSetEx(key string, expiration time.Duration, value string) *StatusCmd {
+	cmd := NewStatusCmd("PSETEX", key, formatMs(expiration), value)
 	c.Process(cmd)
 	return cmd
 }
 
-func (c *commandable) Set(key, value string) *StatusCmd {
-	cmd := NewStatusCmd("SET", key, value)
+func (c *commandable) Set(key, value string, expiration time.Duration) *StatusCmd {
+	args := []string{"SET", key, value}
+	if expiration > 0 {
+		if usePrecise(expiration) {
+			args = append(args, "PX", formatMs(expiration))
+		} else {
+			args = append(args, "EX", formatSec(expiration))
+		}
+	}
+	cmd := NewStatusCmd(args...)
 	c.Process(cmd)
 	return cmd
 }
@@ -453,14 +468,35 @@ func (c *commandable) SetBit(key string, offset int64, value int) *IntCmd {
 	return cmd
 }
 
-func (c *commandable) SetEx(key string, dur time.Duration, value string) *StatusCmd {
-	cmd := NewStatusCmd("SETEX", key, strconv.FormatInt(int64(dur/time.Second), 10), value)
+func (c *commandable) SetEx(key string, expiration time.Duration, value string) *StatusCmd {
+	cmd := NewStatusCmd("SETEX", key, formatSec(expiration), value)
 	c.Process(cmd)
 	return cmd
 }
 
-func (c *commandable) SetNX(key, value string) *BoolCmd {
-	cmd := NewBoolCmd("SETNX", key, value)
+func (c *commandable) SetNX(key, value string, expiration time.Duration) *BoolCmd {
+	var cmd *BoolCmd
+	if expiration == 0 {
+		// Use old `SETNX` to support old Redis versions.
+		cmd = NewBoolCmd("SETNX", key, value)
+	} else {
+		if usePrecise(expiration) {
+			cmd = NewBoolCmd("SET", key, value, "PX", formatMs(expiration), "NX")
+		} else {
+			cmd = NewBoolCmd("SET", key, value, "EX", formatSec(expiration), "NX")
+		}
+	}
+	c.Process(cmd)
+	return cmd
+}
+
+func (c *Client) SetXX(key, value string, expiration time.Duration) *BoolCmd {
+	var cmd *BoolCmd
+	if usePrecise(expiration) {
+		cmd = NewBoolCmd("SET", key, value, "PX", formatMs(expiration), "XX")
+	} else {
+		cmd = NewBoolCmd("SET", key, value, "EX", formatSec(expiration), "XX")
+	}
 	c.Process(cmd)
 	return cmd
 }
diff --git a/commands_test.go b/commands_test.go
index dad515a..6cae06d 100644
--- a/commands_test.go
+++ b/commands_test.go
@@ -149,7 +149,7 @@ var _ = Describe("Commands", func() {
 			Expect(debug.Err()).To(HaveOccurred())
 			Expect(debug.Err().Error()).To(Equal("ERR no such key"))
 
-			client.Set("foo", "bar")
+			client.Set("foo", "bar", 0)
 			debug = client.DebugObject("foo")
 			Expect(debug.Err()).NotTo(HaveOccurred())
 			Expect(debug.Val()).To(ContainSubstring(`serializedlength:4`))
@@ -162,10 +162,10 @@ var _ = Describe("Commands", func() {
 	Describe("keys", func() {
 
 		It("should Del", func() {
-			set := client.Set("key1", "Hello")
+			set := client.Set("key1", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
-			set = client.Set("key2", "World")
+			set = client.Set("key2", "World", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -175,7 +175,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Dump", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -185,7 +185,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Exists", func() {
-			set := client.Set("key1", "Hello")
+			set := client.Set("key1", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -199,7 +199,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Expire", func() {
-			set := client.Set("key", "Hello")
+			set := client.Set("key", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -211,7 +211,7 @@ var _ = Describe("Commands", func() {
 			Expect(ttl.Err()).NotTo(HaveOccurred())
 			Expect(ttl.Val()).To(Equal(10 * time.Second))
 
-			set = client.Set("key", "Hello World")
+			set = client.Set("key", "Hello World", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -221,7 +221,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should ExpireAt", func() {
-			set := client.Set("key", "Hello")
+			set := client.Set("key", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -261,7 +261,7 @@ var _ = Describe("Commands", func() {
 			Expect(migrate.Err()).NotTo(HaveOccurred())
 			Expect(migrate.Val()).To(Equal("NOKEY"))
 
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -275,7 +275,7 @@ var _ = Describe("Commands", func() {
 			Expect(move.Err()).NotTo(HaveOccurred())
 			Expect(move.Val()).To(Equal(false))
 
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -299,7 +299,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Object", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -317,7 +317,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Persist", func() {
-			set := client.Set("key", "Hello")
+			set := client.Set("key", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -339,7 +339,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should PExpire", func() {
-			set := client.Set("key", "Hello")
+			set := client.Set("key", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -359,7 +359,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should PExpireAt", func() {
-			set := client.Set("key", "Hello")
+			set := client.Set("key", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -379,7 +379,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should PTTL", func() {
-			set := client.Set("key", "Hello")
+			set := client.Set("key", "Hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -399,7 +399,7 @@ var _ = Describe("Commands", func() {
 			Expect(randomKey.Err()).To(Equal(redis.Nil))
 			Expect(randomKey.Val()).To(Equal(""))
 
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -409,7 +409,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Rename", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -423,7 +423,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should RenameNX", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -437,7 +437,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Restore", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -481,7 +481,7 @@ var _ = Describe("Commands", func() {
 			Expect(ttl.Err()).NotTo(HaveOccurred())
 			Expect(ttl.Val() < 0).To(Equal(true))
 
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -495,7 +495,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Type", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -512,7 +512,7 @@ var _ = Describe("Commands", func() {
 
 		It("should Scan", func() {
 			for i := 0; i < 1000; i++ {
-				set := client.Set(fmt.Sprintf("key%d", i), "hello")
+				set := client.Set(fmt.Sprintf("key%d", i), "hello", 0)
 				Expect(set.Err()).NotTo(HaveOccurred())
 			}
 
@@ -583,7 +583,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should BitCount", func() {
-			set := client.Set("key", "foobar")
+			set := client.Set("key", "foobar", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -601,11 +601,11 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should BitOpAnd", func() {
-			set := client.Set("key1", "1")
+			set := client.Set("key1", "1", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
-			set = client.Set("key2", "0")
+			set = client.Set("key2", "0", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -619,11 +619,11 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should BitOpOr", func() {
-			set := client.Set("key1", "1")
+			set := client.Set("key1", "1", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
-			set = client.Set("key2", "0")
+			set = client.Set("key2", "0", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -637,11 +637,11 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should BitOpXor", func() {
-			set := client.Set("key1", "\xff")
+			set := client.Set("key1", "\xff", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
-			set = client.Set("key2", "\x0f")
+			set = client.Set("key2", "\x0f", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -655,7 +655,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should BitOpNot", func() {
-			set := client.Set("key1", "\x00")
+			set := client.Set("key1", "\x00", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -669,7 +669,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Decr", func() {
-			set := client.Set("key", "10")
+			set := client.Set("key", "10", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -677,7 +677,7 @@ var _ = Describe("Commands", func() {
 			Expect(decr.Err()).NotTo(HaveOccurred())
 			Expect(decr.Val()).To(Equal(int64(9)))
 
-			set = client.Set("key", "234293482390480948029348230948")
+			set = client.Set("key", "234293482390480948029348230948", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -687,7 +687,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should DecrBy", func() {
-			set := client.Set("key", "10")
+			set := client.Set("key", "10", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -701,7 +701,7 @@ var _ = Describe("Commands", func() {
 			Expect(get.Err()).To(Equal(redis.Nil))
 			Expect(get.Val()).To(Equal(""))
 
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -729,7 +729,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should GetRange", func() {
-			set := client.Set("key", "This is a string")
+			set := client.Set("key", "This is a string", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -765,7 +765,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should Incr", func() {
-			set := client.Set("key", "10")
+			set := client.Set("key", "10", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -779,7 +779,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should IncrBy", func() {
-			set := client.Set("key", "10")
+			set := client.Set("key", "10", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -789,7 +789,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should IncrByFloat", func() {
-			set := client.Set("key", "10.50")
+			set := client.Set("key", "10.50", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -797,7 +797,7 @@ var _ = Describe("Commands", func() {
 			Expect(incrByFloat.Err()).NotTo(HaveOccurred())
 			Expect(incrByFloat.Val()).To(Equal(10.6))
 
-			set = client.Set("key", "5.0e3")
+			set = client.Set("key", "5.0e3", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -848,8 +848,21 @@ var _ = Describe("Commands", func() {
 			Expect(get.Val()).To(Equal("hello"))
 		})
 
+		It("should Set with expiration", func() {
+			err := client.Set("key", "hello", 100*time.Millisecond).Err()
+			Expect(err).NotTo(HaveOccurred())
+
+			val, err := client.Get("key").Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(val).To(Equal("hello"))
+
+			Eventually(func() error {
+				return client.Get("foo").Err()
+			}, "1s", "100ms").Should(Equal(redis.Nil))
+		})
+
 		It("should SetGet", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -869,11 +882,11 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should SetNX", func() {
-			setNX := client.SetNX("key", "hello")
+			setNX := client.SetNX("key", "hello", 0)
 			Expect(setNX.Err()).NotTo(HaveOccurred())
 			Expect(setNX.Val()).To(Equal(true))
 
-			setNX = client.SetNX("key", "hello2")
+			setNX = client.SetNX("key", "hello2", 0)
 			Expect(setNX.Err()).NotTo(HaveOccurred())
 			Expect(setNX.Val()).To(Equal(false))
 
@@ -882,8 +895,39 @@ var _ = Describe("Commands", func() {
 			Expect(get.Val()).To(Equal("hello"))
 		})
 
+		It("should SetNX with expiration", func() {
+			isSet, err := client.SetNX("key", "hello", time.Second).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(isSet).To(Equal(true))
+
+			isSet, err = client.SetNX("key", "hello2", time.Second).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(isSet).To(Equal(false))
+
+			val, err := client.Get("key").Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(val).To(Equal("hello"))
+		})
+
+		It("should SetXX", func() {
+			isSet, err := client.SetXX("key", "hello2", time.Second).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(isSet).To(Equal(false))
+
+			err = client.Set("key", "hello", time.Second).Err()
+			Expect(err).NotTo(HaveOccurred())
+
+			isSet, err = client.SetXX("key", "hello2", time.Second).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(isSet).To(Equal(true))
+
+			val, err := client.Get("key").Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(val).To(Equal("hello2"))
+		})
+
 		It("should SetRange", func() {
-			set := client.Set("key", "Hello World")
+			set := client.Set("key", "Hello World", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -897,7 +941,7 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should StrLen", func() {
-			set := client.Set("key", "hello")
+			set := client.Set("key", "hello", 0)
 			Expect(set.Err()).NotTo(HaveOccurred())
 			Expect(set.Val()).To(Equal("OK"))
 
@@ -2176,7 +2220,7 @@ var _ = Describe("Commands", func() {
 			Expect(err).NotTo(HaveOccurred())
 
 			return multi.Exec(func() error {
-				multi.Set("key", strconv.FormatInt(v+1, 10))
+				multi.Set("key", strconv.FormatInt(v+1, 10), 0)
 				return nil
 			})
 		}
@@ -2187,7 +2231,7 @@ var _ = Describe("Commands", func() {
 				n = 1000
 			}
 
-			err := client.Set("key", "0").Err()
+			err := client.Set("key", "0", 0).Err()
 			Expect(err).NotTo(HaveOccurred())
 
 			wg := &sync.WaitGroup{}
diff --git a/example_test.go b/example_test.go
index ddcc1bf..bf94040 100644
--- a/example_test.go
+++ b/example_test.go
@@ -36,7 +36,7 @@ func ExampleNewFailoverClient() {
 }
 
 func ExampleClient() {
-	if err := client.Set("foo", "bar").Err(); err != nil {
+	if err := client.Set("foo", "bar", 0).Err(); err != nil {
 		panic(err)
 	}
 
@@ -57,7 +57,7 @@ func ExampleClient_Incr() {
 
 func ExampleClient_Pipelined() {
 	cmds, err := client.Pipelined(func(c *redis.Pipeline) error {
-		c.Set("key1", "hello1")
+		c.Set("key1", "hello1", 0)
 		c.Get("key1")
 		return nil
 	})
@@ -73,7 +73,7 @@ func ExampleClient_Pipelined() {
 
 func ExamplePipeline() {
 	pipeline := client.Pipeline()
-	set := pipeline.Set("key1", "hello1")
+	set := pipeline.Set("key1", "hello1", 0)
 	get := pipeline.Get("key1")
 	cmds, err := pipeline.Exec()
 	fmt.Println(cmds, err)
@@ -93,7 +93,7 @@ func ExampleMulti() {
 		n, _ := strconv.ParseInt(s, 10, 64)
 
 		return tx.Exec(func() error {
-			tx.Set("key", strconv.FormatInt(n+1, 10))
+			tx.Set("key", strconv.FormatInt(n+1, 10), 0)
 			return nil
 		})
 	}
diff --git a/multi_test.go b/multi_test.go
index 801bb19..eab870c 100644
--- a/multi_test.go
+++ b/multi_test.go
@@ -32,7 +32,7 @@ var _ = Describe("Multi", func() {
 			get *redis.StringCmd
 		)
 		cmds, err := multi.Exec(func() error {
-			set = multi.Set("key", "hello")
+			set = multi.Set("key", "hello", 0)
 			get = multi.Get("key")
 			return nil
 		})
@@ -53,9 +53,9 @@ var _ = Describe("Multi", func() {
 		}()
 
 		cmds, err := multi.Exec(func() error {
-			multi.Set("key1", "hello1")
+			multi.Set("key1", "hello1", 0)
 			multi.Discard()
-			multi.Set("key2", "hello2")
+			multi.Set("key2", "hello2", 0)
 			return nil
 		})
 		Expect(err).NotTo(HaveOccurred())
diff --git a/pipeline_test.go b/pipeline_test.go
index c55f99d..9d2770d 100644
--- a/pipeline_test.go
+++ b/pipeline_test.go
@@ -25,12 +25,12 @@ var _ = Describe("Pipelining", func() {
 	})
 
 	It("should pipeline", func() {
-		set := client.Set("key2", "hello2")
+		set := client.Set("key2", "hello2", 0)
 		Expect(set.Err()).NotTo(HaveOccurred())
 		Expect(set.Val()).To(Equal("OK"))
 
 		pipeline := client.Pipeline()
-		set = pipeline.Set("key1", "hello1")
+		set = pipeline.Set("key1", "hello1", 0)
 		get := pipeline.Get("key2")
 		incr := pipeline.Incr("key3")
 		getNil := pipeline.Get("key4")
diff --git a/redis_test.go b/redis_test.go
index fc1f0b3..ed53b9a 100644
--- a/redis_test.go
+++ b/redis_test.go
@@ -109,7 +109,7 @@ var _ = Describe("Client", func() {
 		defer db1.Close()
 
 		Expect(db1.Get("key").Err()).To(Equal(redis.Nil))
-		Expect(db1.Set("key", "value").Err()).NotTo(HaveOccurred())
+		Expect(db1.Set("key", "value", 0).Err()).NotTo(HaveOccurred())
 
 		Expect(client.Get("key").Err()).To(Equal(redis.Nil))
 		Expect(db1.Get("key").Val()).To(Equal("value"))
@@ -253,7 +253,7 @@ func BenchmarkRedisSet(b *testing.B) {
 	b.StartTimer()
 
 	for i := 0; i < b.N; i++ {
-		if err := client.Set("key", "hello").Err(); err != nil {
+		if err := client.Set("key", "hello", 0).Err(); err != nil {
 			panic(err)
 		}
 	}
@@ -281,7 +281,7 @@ func BenchmarkRedisGet(b *testing.B) {
 	client := redis.NewTCPClient(&redis.Options{
 		Addr: redisAddr,
 	})
-	if err := client.Set("key", "hello").Err(); err != nil {
+	if err := client.Set("key", "hello", 0).Err(); err != nil {
 		b.Fatal(err)
 	}
 	b.StartTimer()
@@ -318,7 +318,7 @@ func BenchmarkSetExpire(b *testing.B) {
 	b.StartTimer()
 
 	for i := 0; i < b.N; i++ {
-		if err := client.Set("key", "hello").Err(); err != nil {
+		if err := client.Set("key", "hello", 0).Err(); err != nil {
 			b.Fatal(err)
 		}
 		if err := client.Expire("key", time.Second).Err(); err != nil {
@@ -336,7 +336,7 @@ func BenchmarkPipeline(b *testing.B) {
 
 	for i := 0; i < b.N; i++ {
 		_, err := client.Pipelined(func(pipe *redis.Pipeline) error {
-			pipe.Set("key", "hello")
+			pipe.Set("key", "hello", 0)
 			pipe.Expire("key", time.Second)
 			return nil
 		})
diff --git a/sentinel_test.go b/sentinel_test.go
index 8e6bf86..6fc2f4f 100644
--- a/sentinel_test.go
+++ b/sentinel_test.go
@@ -36,7 +36,7 @@ var _ = Describe("Sentinel", func() {
 		defer client.Close()
 
 		// Set value on master, verify
-		err = client.Set("foo", "master").Err()
+		err = client.Set("foo", "master", 0).Err()
 		Expect(err).NotTo(HaveOccurred())
 
 		val, err := master.Get("foo").Result()