diff --git a/engine_group.go b/engine_group.go
index dd1e6380..5e659aaf 100644
--- a/engine_group.go
+++ b/engine_group.go
@@ -17,7 +17,7 @@ type EngineGroup struct {
 	policy GroupPolicy
 }
 
-func NewGroup(args1 interface{}, args2 interface{}, policies ...GroupPolicy) (*EngineGroup, error) {
+func NewEngineGroup(args1 interface{}, args2 interface{}, policies ...GroupPolicy) (*EngineGroup, error) {
 	var eg EngineGroup
 	if len(policies) > 0 {
 		eg.policy = policies[0]
diff --git a/engine_group_policy.go b/engine_group_policy.go
index 73b1226f..c3e528ad 100644
--- a/engine_group_policy.go
+++ b/engine_group_policy.go
@@ -68,16 +68,17 @@ func NewRoundRobinPolicy() *RoundRobinPolicy {
 }
 
 func (policy *RoundRobinPolicy) Slave(g *EngineGroup) *Engine {
+	var slaves = g.Slaves()
 	var pos int
 	policy.lock.Lock()
 	policy.pos++
-	if policy.pos >= len(g.Slaves()) {
+	if policy.pos >= len(slaves) {
 		policy.pos = 0
 	}
 	pos = policy.pos
 	policy.lock.Unlock()
 
-	return g.Slaves()[pos]
+	return slaves[pos]
 }
 
 type WeightRoundRobinPolicy struct {