diff --git a/docs/API.md b/docs/API.md
index 52763578..75971fd5 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -9,7 +9,7 @@ title: API
 - [Standard Libraries](#standard-libraries)
 - [SRFI Libraries](#srfi-libraries)
 - [Cyclone Libraries](#cyclone-libraries)
-- [Cyclone Compiler API](#cyclone-compiler-api)
+- [Internal Compiler API](#internal-compiler-api)
 - [C API](#c-api)
 - [Index](#index)
 
@@ -58,13 +58,15 @@ Cyclone supports the following [Scheme Requests for Implementation (SRFI)](http:
 
 # Cyclone Libraries
 
-These libraries are provided by Cyclone with a stable API that is unlikely to change.
+These libraries are provided by Cyclone with a stable API that is unlikely to change:
 
+- [`cyclone concurrent`](api/cyclone/concurrent) - A helper library for writing concurrent code.
+- [`cyclone match`](api/cyclone/match) - A hygienic pattern matcher based on Alex Shinn's portable `match.scm`.
+- [`cyclone test`](api/cyclone/test) - A unit testing framework ported from `(chibi test)`.
 - [`scheme cyclone array-list`](api/scheme/cyclone/array-list)
-- [`scheme cyclone pretty-print`](api/scheme/cyclone/pretty-print)
-- [`scheme cyclone test`](api/scheme/cyclone/test)
+- [`scheme cyclone pretty-print`](api/scheme/cyclone/pretty-print) - A pretty printer.
 
-# Cyclone Compiler API
+# Internal Compiler API
 
 These libraries are used by the Cyclone compiler. Some of these are stable and unlikely to change, whereas others could change as the compiler evolves.
 
@@ -73,7 +75,6 @@ These libraries are used by the Cyclone compiler. Some of these are stable and u
 - [`scheme cyclone common`](api/scheme/cyclone/common)
 - [`scheme cyclone cps-optimizations`](api/scheme/cyclone/cps-optimizations)
 - [`scheme cyclone libraries`](api/scheme/cyclone/libraries)
-- [`scheme cyclone match`](api/scheme/cyclone/match)
 - [`scheme cyclone primitives`](api/scheme/cyclone/primitives)
 - [`scheme cyclone transforms`](api/scheme/cyclone/transforms)
 - [`scheme cyclone util`](api/scheme/cyclone/util)
diff --git a/docs/api/scheme/cyclone/ast.md b/docs/api/scheme/cyclone/ast.md
index d7edcf5e..1b0dfde9 100644
--- a/docs/api/scheme/cyclone/ast.md
+++ b/docs/api/scheme/cyclone/ast.md
@@ -59,3 +59,4 @@ The `(scheme cyclone ast)` library defines abstract syntax tree types used durin
 # ast:ast->pp-sexp
 
     (ast:ast->pp-sexp exp)
+
diff --git a/docs/api/scheme/cyclone/match.md b/docs/api/scheme/cyclone/match.md
index ca3718c0..cd7ab13b 100644
--- a/docs/api/scheme/cyclone/match.md
+++ b/docs/api/scheme/cyclone/match.md
@@ -3,6 +3,11 @@ layout: main
 title: API
 ---
 
+---
+layout: main
+title: API
+---
+
 # Match Library
 
 The `(scheme cyclone match)` library provides a hygienic pattern matcher, based on Alex Shinn's portable `match.scm`.
diff --git a/docs/api/scheme/cyclone/test.md b/docs/api/scheme/cyclone/test.md
index 5ce6c242..59464525 100644
--- a/docs/api/scheme/cyclone/test.md
+++ b/docs/api/scheme/cyclone/test.md
@@ -3,6 +3,11 @@ layout: main
 title: API
 ---
 
+---
+layout: main
+title: API
+---
+
 # Test Library
 
 The `(scheme cyclone test)` library contains a testing framework ported from `(chibi test)` which in turn was ported from CHICKEN.
diff --git a/docs/api/srfi/18.md b/docs/api/srfi/18.md
index 7ff6d547..994b1664 100644
--- a/docs/api/srfi/18.md
+++ b/docs/api/srfi/18.md
@@ -109,9 +109,9 @@ NOTE: Creates a new mutex by allocating it on the heap. This is different than o
 
 # mutex-lock! 
 
-    (mutex-lock! mutex)
+    (mutex-lock! mutex [timeout])
 
-Lock the given mutex if it is unlocked.  If the mutex is currently locked, the current thread waits until the mutex is unlocked.
+Lock the given mutex if it is unlocked.  If the mutex is currently locked, the current thread waits until the mutex is unlocked, or until the timeout is reached if `timeout` is supplied.
 
 # mutex-unlock!