diff --git a/specs/simple-serialize.md b/specs/simple-serialize.md
index 7076b6410..8d9c33103 100644
--- a/specs/simple-serialize.md
+++ b/specs/simple-serialize.md
@@ -11,16 +11,22 @@
     - [Typing](#typing)
         - [Basic types](#basic-types)
         - [Composite types](#composite-types)
+        - [Variable-size and fixed-size](#variable-size-and-fixed-size)
         - [Aliases](#aliases)
         - [Default values](#default-values)
+            - [`is_empty`](#is_empty)
         - [Illegal types](#illegal-types)
     - [Serialization](#serialization)
         - [`uintN`](#uintn)
         - [`boolean`](#boolean)
         - [`null`](#null)
+        - [`Bitvector[N]`](#bitvectorn)
+        - [`Bitlist[N]`](#bitlistn)
         - [Vectors, containers, lists, unions](#vectors-containers-lists-unions)
     - [Deserialization](#deserialization)
     - [Merkleization](#merkleization)
+        - [Merkleization of `Bitvector[N]`](#merkleization-of-bitvectorn)
+        - [`Bitlist[N]`](#bitlistn-1)
     - [Self-signed containers](#self-signed-containers)
     - [Implementations](#implementations)