diff --git a/src/main/java/com/github/hcsp/datatype/Light.java b/src/main/java/com/github/hcsp/datatype/Light.java
index bf1c09e..113b5f9 100644
--- a/src/main/java/com/github/hcsp/datatype/Light.java
+++ b/src/main/java/com/github/hcsp/datatype/Light.java
@@ -13,7 +13,8 @@ public Light(Boolean on) {
 
     // 当灯亮时返回true，灭和未知状态返回false
     public boolean isOn() {
-        return on;
+
+        return on != null && on;
     }
 
     public Boolean isOnRawValue() {