diff --git a/samples/trace_printk/trace-printk.c b/samples/trace_printk/trace-printk.c
index e9e0040..7affc3b 100644
--- a/samples/trace_printk/trace-printk.c
+++ b/samples/trace_printk/trace-printk.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0-only
 #include <linux/module.h>
 #include <linux/kthread.h>
 #include <linux/irq_work.h>