diff --git a/openwrt/target/linux/package/switch/src/switch-robo.c b/openwrt/target/linux/package/switch/src/switch-robo.c
index b23fca644..eb93f4b98 100644
--- a/openwrt/target/linux/package/switch/src/switch-robo.c
+++ b/openwrt/target/linux/package/switch/src/switch-robo.c
@@ -315,6 +315,8 @@ static int handle_vlan_port_read(void *driver, char *buf, int nr)
 		}
 	}
 
+	buf[len] = '\0';
+
 	return len;
 }