diff --git a/Doc/lib/libzlib.tex b/Doc/lib/libzlib.tex
index 10178da..db62a27 100644
--- a/Doc/lib/libzlib.tex
+++ b/Doc/lib/libzlib.tex
@@ -8,11 +8,10 @@
 
 For applications that require data compression, the functions in this
 module allow compression and decompression, using the zlib library.
-The zlib library has its own home page at
-\url{http://www.gzip.org/zlib/}.  Version 1.2.1 is the
-most recent version as of October 2004; use a later version if one
-is available.  There are known incompatibilities between the Python
-module and earlier versions of the zlib library.
+The zlib library has its own home page at \url{http://www.gzip.org/zlib/}.  
+There are known incompatibilities between the Python module and
+versions of the zlib library earlier than 1.1.3; 1.1.3 has a security
+vulnerability, so we recommend using 1.1.4 or later.
 
 The available exception and functions in this module are: