diff --git a/SUMMARY.md b/SUMMARY.md
index be1ac08b..b33373d6 100644
--- a/SUMMARY.md
+++ b/SUMMARY.md
@@ -108,6 +108,7 @@
   * [Task](appendix_b.md#task)
 * [Appendix C: Pointfree Utilities](appendix_c.md)
   * [add](appendix_c.md#add)
+  * [append](appendix_c.md#append)
   * [chain](appendix_c.md#chain)
   * [concat](appendix_c.md#concat)
   * [eq](appendix_c.md#eq)