diff --git a/Doc/libctb.tex b/Doc/libctb.tex
index 1cda336..a5aab71 100644
--- a/Doc/libctb.tex
+++ b/Doc/libctb.tex
@@ -4,7 +4,7 @@
 
 This module provides a partial interface to the Macintosh
 Communications Toolbox. Currently, only Connection Manager tools are
-supported. 
+supported.  It may not be available in all Mac Python versions.
 
 \begin{datadesc}{error}
 The exception raised on errors.