diff --git a/cmd/envtocsv/main.go b/cmd/envtocsv/main.go
index e8006d1..4b2622a 100644
--- a/cmd/envtocsv/main.go
+++ b/cmd/envtocsv/main.go
@@ -7,6 +7,8 @@
 //
 // You should have received a copy of the CC0 Public Domain Dedication along with
 // this software. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
+//
+// SPDX-License-Identifier: CC0-1.0
 
 package main