diff --git a/docs/api/scheme/cyclone/cps-optimizations.md b/docs/api/scheme/cyclone/cps-optimizations.md
index aa004321..356019e1 100644
--- a/docs/api/scheme/cyclone/cps-optimizations.md
+++ b/docs/api/scheme/cyclone/cps-optimizations.md
@@ -2,6 +2,8 @@
 
 The `(scheme cyclone optimizations)` library performs CPS analysis and optimizations.
 
+*This library is used internally by the compiler and its API may change at any time.*
+
 - [`optimize-cps`](#optimize-cps)
 - [`analyze-cps`](#analyze-cps)
 - [`opt:contract`](#optcontract)
diff --git a/docs/api/scheme/cyclone/libraries.md b/docs/api/scheme/cyclone/libraries.md
index 2fc1c75b..c5281d6d 100644
--- a/docs/api/scheme/cyclone/libraries.md
+++ b/docs/api/scheme/cyclone/libraries.md
@@ -2,6 +2,8 @@
 
 The `(scheme cyclone libraries)` library implements r7rs libraries.
 
+*This library is used internally by the compiler and its API may change at any time.*
+
 - [`library?`](#library)
 - [`lib:list->import-set`](#liblist-import-set)
 - [`lib:name`](#libname)
diff --git a/docs/api/scheme/cyclone/primitives.md b/docs/api/scheme/cyclone/primitives.md
index e70909fa..4cf13c25 100644
--- a/docs/api/scheme/cyclone/primitives.md
+++ b/docs/api/scheme/cyclone/primitives.md
@@ -2,6 +2,8 @@
 
 The `(scheme cyclone primitives)` library contains information about Cyclone's scheme primitives.
 
+*This library is used internally by the compiler and its API may change at any time.*
+
 - [`prim?`](#prim)
 - [`*primitives*`](#primitives)
 - [`*primitives-num-args*`](#primitives-num-args)
diff --git a/docs/api/scheme/cyclone/transforms.md b/docs/api/scheme/cyclone/transforms.md
index d5a59365..98c10618 100644
--- a/docs/api/scheme/cyclone/transforms.md
+++ b/docs/api/scheme/cyclone/transforms.md
@@ -2,6 +2,8 @@
 
 The `(scheme cyclone transforms)` library performs Scheme-to-Scheme transformations, and also contains various utility functions used by the compiler.
 
+*This library is used internally by the compiler and its API may change at any time.*
+
 - [`*defined-macros*          `](#*defined-macros)
 - [`*do-code-gen*             `](#*do-code-gen)
 - [`*primitives*              `](#*primitives)
diff --git a/docs/api/scheme/cyclone/util.md b/docs/api/scheme/cyclone/util.md
index ac0b4c9d..309a1830 100644
--- a/docs/api/scheme/cyclone/util.md
+++ b/docs/api/scheme/cyclone/util.md
@@ -2,6 +2,8 @@
 
 The `(scheme cyclone util`) library contains various utility functions used internally the compiler.
 
+*This library is used internally by the compiler and its API may change at any time.*
+
 - [`Cyc-er-compare?            `](#cyc-er-compare)
 - [`Cyc-er-rename              `](#cyc-er-rename)
 - [`app?                       `](#app)