diff --git a/specs/casper_sharding_v2.1.md b/specs/casper_sharding_v2.1.md
index 382d1df73..41ef3cfca 100644
--- a/specs/casper_sharding_v2.1.md
+++ b/specs/casper_sharding_v2.1.md
@@ -439,4 +439,7 @@ Slashing conditions may include:
     Proof of custody secret leak
     Proof of custody wrong custody bit
     Proof of custody no secret reveal
-    RANDAO leak
\ No newline at end of file
+    RANDAO leak
+
+## Copyright
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).