diff --git a/pool/tree/pool.go b/pool/tree/pool.go
index 60c205f..7b1afef 100644
--- a/pool/tree/pool.go
+++ b/pool/tree/pool.go
@@ -1012,7 +1012,7 @@ LOOP:
 					continue
 				}
 
-				p.addClientToMap(cnrNode.Hash(), treeCl)
+				treeCl = p.addClientToMap(cnrNode.Hash(), treeCl)
 			}
 			attempts--
 
@@ -1047,10 +1047,16 @@ func (p *Pool) getClientFromMap(hash uint64) (client, bool) {
 	return cl, ok
 }
 
-func (p *Pool) addClientToMap(hash uint64, cl client) {
+func (p *Pool) addClientToMap(hash uint64, cl client) client {
 	p.mutex.Lock()
+	defer p.mutex.Unlock()
+
+	if old, ok := p.clientMap[hash]; ok {
+		_ = cl.close()
+		return old
+	}
 	p.clientMap[hash] = cl
-	p.mutex.Unlock()
+	return cl
 }
 
 func (p *Pool) deleteClientFromMap(hash uint64) {