diff --git a/Documentation/api.md b/Documentation/api.md
index 1ecaf0a9f..95a8e2c6b 100644
--- a/Documentation/api.md
+++ b/Documentation/api.md
@@ -202,6 +202,32 @@ If the TTL has expired, the key will have been deleted, and you will be returned
 }
 ```
 
+The TTL could be unset to avoid expiration through update operation:
+
+```sh
+curl -L http://127.0.0.1:4001/v2/keys/foo -XPUT -d value=bar -d ttl= -d prevExist=true
+```
+
+```json
+{
+    "action": "update",
+    "node": {
+        "createdIndex": 5,
+        "key": "/foo",
+        "modifiedIndex": 6,
+        "value": "bar"
+    }
+    "prevNode": {
+        "createdIndex": 5,
+        "expiration": "2013-12-04T12:01:21.874888581-08:00",
+        "key": "/foo",
+        "modifiedIndex": 5,
+        "ttl": 3,
+        "value": "bar"
+    }
+}
+```
+
 
 ### Waiting for a change
 
diff --git a/server/v2/tests/put_handler_test.go b/server/v2/tests/put_handler_test.go
index ec7267847..d6416b2a2 100644
--- a/server/v2/tests/put_handler_test.go
+++ b/server/v2/tests/put_handler_test.go
@@ -194,6 +194,42 @@ func TestV2UpdateKeyFailOnMissingDirectory(t *testing.T) {
 	})
 }
 
+// Ensures that a key could update TTL.
+//
+//   $ curl -X PUT localhost:4001/v2/keys/foo -d value=XXX
+//   $ curl -X PUT localhost:4001/v2/keys/foo -d value=XXX -d ttl=1000 -d prevExist=true
+//   $ curl -X PUT localhost:4001/v2/keys/foo -d value=XXX -d ttl= -d prevExist=true
+//
+func TestV2UpdateKeySuccessWithTTL(t *testing.T) {
+	tests.RunServer(func(s *server.Server) {
+		v := url.Values{}
+		v.Set("value", "XXX")
+		resp, _ := tests.PutForm(fmt.Sprintf("%s%s", s.URL(), "/v2/keys/foo"), v)
+		assert.Equal(t, resp.StatusCode, http.StatusCreated)
+		node := (tests.ReadBodyJSON(resp)["node"]).(map[string]interface{})
+		createdIndex := node["createdIndex"]
+
+		v.Set("ttl", "1000")
+		v.Set("prevExist", "true")
+		resp, _ = tests.PutForm(fmt.Sprintf("%s%s", s.URL(), "/v2/keys/foo"), v)
+		assert.Equal(t, resp.StatusCode, http.StatusOK)
+		node = (tests.ReadBodyJSON(resp)["node"]).(map[string]interface{})
+		assert.Equal(t, node["value"], "XXX", "")
+		assert.Equal(t, node["ttl"], 1000, "")
+		assert.NotEqual(t, node["expiration"], "", "")
+		assert.Equal(t, node["createdIndex"], createdIndex, "")
+
+		v.Del("ttl")
+		resp, _ = tests.PutForm(fmt.Sprintf("%s%s", s.URL(), "/v2/keys/foo"), v)
+		assert.Equal(t, resp.StatusCode, http.StatusOK)
+		node = (tests.ReadBodyJSON(resp)["node"]).(map[string]interface{})
+		assert.Equal(t, node["value"], "XXX", "")
+		assert.Equal(t, node["ttl"], nil, "")
+		assert.Equal(t, node["expiration"], nil, "")
+		assert.Equal(t, node["createdIndex"], createdIndex, "")
+	})
+}
+
 // Ensures that a key is set only if the previous index matches.
 //
 //   $ curl -X PUT localhost:4001/v2/keys/foo/bar -d value=XXX
diff --git a/store/node.go b/store/node.go
index 95d5d067d..f11619a60 100644
--- a/store/node.go
+++ b/store/node.go
@@ -310,6 +310,7 @@ func (n *node) UpdateTTL(expireTime time.Time) {
 	if !n.IsPermanent() {
 		if expireTime.IsZero() {
 			// from ttl to permanent
+			n.ExpireTime = expireTime
 			// remove from ttl heap
 			n.store.ttlKeyHeap.remove(n)
 		} else {