diff --git a/include/mbedtls/pem.h b/include/mbedtls/pem.h
index cc617a9..2fe19d0 100644
--- a/include/mbedtls/pem.h
+++ b/include/mbedtls/pem.h
@@ -135,6 +135,9 @@
  * \param olen      The address at which to store the total length written
  *                  or required (if \p buf_len is not enough).
  *
+ * \note            Newlines are automatically appended to both header and
+ *                  footer.
+ *
  * \note            You may pass \c NULL for \p buf and \c 0 for \p buf_len
  *                  to request the length of the resulting PEM buffer in
  *                  `*olen`.