diff --git a/commands.go b/commands.go
index 5ac7de7..4511284 100644
--- a/commands.go
+++ b/commands.go
@@ -788,10 +788,14 @@ func (c *cmdable) SetNX(key string, value interface{}, expiration time.Duration)
 // Zero expiration means the key has no expiration time.
 func (c *cmdable) SetXX(key string, value interface{}, expiration time.Duration) *BoolCmd {
 	var cmd *BoolCmd
-	if usePrecise(expiration) {
-		cmd = NewBoolCmd("set", key, value, "px", formatMs(expiration), "xx")
+	if expiration == 0 {
+		cmd = NewBoolCmd("set", key, value, "xx")
 	} else {
-		cmd = NewBoolCmd("set", key, value, "ex", formatSec(expiration), "xx")
+		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 2db90e2..7da5f2a 100644
--- a/commands_test.go
+++ b/commands_test.go
@@ -996,6 +996,23 @@ var _ = Describe("Commands", func() {
 		})
 
 		It("should SetXX", func() {
+			isSet, err := client.SetXX("key", "hello2", 0).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(isSet).To(Equal(false))
+
+			err = client.Set("key", "hello", 0).Err()
+			Expect(err).NotTo(HaveOccurred())
+
+			isSet, err = client.SetXX("key", "hello2", 0).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 SetXX with expiration", func() {
 			isSet, err := client.SetXX("key", "hello2", time.Second).Result()
 			Expect(err).NotTo(HaveOccurred())
 			Expect(isSet).To(Equal(false))