diff --git a/service/service-registry.go b/service/service-registry.go
index ca770b6..b0b76fb 100644
--- a/service/service-registry.go
+++ b/service/service-registry.go
@@ -43,6 +43,10 @@ func (mm *MethodMeta) Call(in []reflect.Value) []reflect.Value {
 	return mm.method.Func.Call(in)
 }
 
+func (mm *MethodMeta) ReturnType() reflect.Type {
+	return mm.returnType
+}
+
 func (mm *MethodMeta) ParamValues() (values []reflect.Value, instances []interface{}) {
 	if nil == mm.paramTypes || 0 == len(mm.paramTypes) {
 		return nil, nil