diff --git a/cluster.go b/cluster.go
index b8adedc7..2c6a45ce 100644
--- a/cluster.go
+++ b/cluster.go
@@ -13,10 +13,11 @@ type ClusterClient struct {
 
 	addrs   []string
 	slots   [][]string
-	slotsMx sync.RWMutex // protects slots & addrs cache
+	slotsMx sync.RWMutex // Protects slots and addrs.
 
 	clients   map[string]*Client
-	clientsMx sync.RWMutex
+	closed    bool
+	clientsMx sync.RWMutex // Protects clients and closed.
 
 	opt *ClusterOptions
 
@@ -39,16 +40,24 @@ func NewClusterClient(opt *ClusterOptions) *ClusterClient {
 	return client
 }
 
-// Close closes the cluster client.
+// Close closes the cluster client, releasing any open resources.
+//
+// It is rare to Close a Client, as the Client is meant to be
+// long-lived and shared between many goroutines.
 func (c *ClusterClient) Close() error {
-	// TODO: close should make client unusable
-	c.setSlots(nil)
+	c.clientsMx.Lock()
+
+	if c.closed {
+		return nil
+	}
+	c.closed = true
 	c.resetClients()
+	c.setSlots(nil)
+
+	c.clientsMx.Unlock()
 	return nil
 }
 
-// ------------------------------------------------------------------------
-
 // getClient returns a Client for a given address.
 func (c *ClusterClient) getClient(addr string) (*Client, error) {
 	if addr == "" {
@@ -64,6 +73,10 @@ func (c *ClusterClient) getClient(addr string) (*Client, error) {
 	c.clientsMx.RUnlock()
 
 	c.clientsMx.Lock()
+	if c.closed {
+		return nil, errClosed
+	}
+
 	client, ok = c.clients[addr]
 	if !ok {
 		opt := c.opt.clientOptions()
@@ -83,7 +96,7 @@ func (c *ClusterClient) slotAddrs(slot int) []string {
 	return addrs
 }
 
-// randomClient returns a Client for the first live node.
+// randomClient returns a Client for the first pingable node.
 func (c *ClusterClient) randomClient() (client *Client, err error) {
 	for i := 0; i < 10; i++ {
 		n := rand.Intn(len(c.addrs))
@@ -165,14 +178,12 @@ func (c *ClusterClient) process(cmd Cmder) {
 
 // Closes all clients and returns last error if there are any.
 func (c *ClusterClient) resetClients() (err error) {
-	c.clientsMx.Lock()
 	for addr, client := range c.clients {
 		if e := client.Close(); e != nil {
 			err = e
 		}
 		delete(c.clients, addr)
 	}
-	c.clientsMx.Unlock()
 	return err
 }
 
@@ -231,14 +242,24 @@ func (c *ClusterClient) scheduleReload() {
 // reaper closes idle connections to the cluster.
 func (c *ClusterClient) reaper(ticker *time.Ticker) {
 	for _ = range ticker.C {
+		c.clientsMx.RLock()
+
+		if c.closed {
+			c.clientsMx.RUnlock()
+			return
+		}
+
 		for _, client := range c.clients {
 			pool := client.connPool
-			// pool.First removes idle connections from the pool for us. So
-			// just put returned connection back.
+			// pool.First removes idle connections from the pool and
+			// returns first non-idle connection. So just put returned
+			// connection back.
 			if cn := pool.First(); cn != nil {
 				pool.Put(cn)
 			}
 		}
+
+		c.clientsMx.RUnlock()
 	}
 }