diff --git a/tools/build/feature/test-fortify-source.c b/tools/build/feature/test-fortify-source.c
index c9f398d8786820588da652a7a89ef5c3e729127b..c8a57194f9f29b8f9b2f01114c043e64a1c60d2a 100644
--- a/tools/build/feature/test-fortify-source.c
+++ b/tools/build/feature/test-fortify-source.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 
 int main(void)
diff --git a/tools/build/feature/test-hello.c b/tools/build/feature/test-hello.c
index c9f398d8786820588da652a7a89ef5c3e729127b..c8a57194f9f29b8f9b2f01114c043e64a1c60d2a 100644
--- a/tools/build/feature/test-hello.c
+++ b/tools/build/feature/test-hello.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 
 int main(void)
diff --git a/tools/build/feature/test-setns.c b/tools/build/feature/test-setns.c
index 4a1581ae7a5585c4bb4924802cc2c33956cec7fe..2757c201ed50c26c802745b3db39cc1f3b868df9 100644
--- a/tools/build/feature/test-setns.c
+++ b/tools/build/feature/test-setns.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #define _GNU_SOURCE
 #include <sched.h>