diff --git a/ds18b20/ds18b20.go b/ds18b20/ds18b20.go
index e64d0dc..532c9f2 100644
--- a/ds18b20/ds18b20.go
+++ b/ds18b20/ds18b20.go
@@ -195,3 +195,4 @@ var sleep = time.Sleep
 
 var _ conn.Resource = &Dev{}
 var _ physic.SenseEnv = &Dev{}
+