diff --git a/ChangeLog b/ChangeLog
index b2d34e7..1ca0ecc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2017-10-09  NIIBE Yutaka  <gniibe@fsij.org>
 
+	* example-cdc-gnu-linux/sample.c (main): Support debug option.
+
 	* mcu/sys-gnu-linux.h (debug): New.
 	* mcu/sys-gnu-linux.c: Use debug.
 	* mcu/usb-usbip.c: Use debug.
diff --git a/example-cdc-gnu-linux/sample.c b/example-cdc-gnu-linux/sample.c
index e343f7d..02d394d 100644
--- a/example-cdc-gnu-linux/sample.c
+++ b/example-cdc-gnu-linux/sample.c
@@ -98,8 +98,8 @@ main (int argc, const char *argv[])
   uint8_t count;
   uintptr_t addr;
 
-  (void)argc;
-  (void)argv;
+  if (argc >= 2 && !strncmp (argv[1], "--debug=", 8))
+    debug = strtol (&argv[1][8], NULL, 10);
 
   chopstx_mutex_init (&mtx);
   chopstx_cond_init (&cnd0);