diff --git a/README.md b/README.md
index 2b9b57f..0dde9d7 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,12 @@ Clone this repository and go to source directory, just run make install. During
 make install
 ```
 
+If you need debug messages, please set `EXTRA_CFLAGS=-DDEBUG`
+
+```shell
+make install EXTRA_CFLAGS=-DDEBUG
+```
+
 ## Deb package
 
 1. Prerequisites
diff --git a/nct6687.c b/nct6687.c
index 1c0f64b..ddd7c62 100644
--- a/nct6687.c
+++ b/nct6687.c
@@ -19,7 +19,7 @@
  * Notes:
  *	(1) Total number of voltage and 9 displayed.
  */
-#define DEBUG 1
+// #define DEBUG 1
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/acpi.h>