diff --git a/openbsd-compat/chacha_private.h b/openbsd-compat/chacha_private.h
index 7c3680fa6..2e5c8c1da 100644
--- a/openbsd-compat/chacha_private.h
+++ b/openbsd-compat/chacha_private.h
@@ -1,3 +1,5 @@
+/* OPENBSD ORIGINAL: lib/libc/crypt/chacha_private.h */
+
 /*
 chacha-merged.c version 20080118
 D. J. Bernstein