diff --git a/Doc/library/httplib.rst b/Doc/library/httplib.rst
index 58a59a8..436857c 100644
--- a/Doc/library/httplib.rst
+++ b/Doc/library/httplib.rst
@@ -73,9 +73,8 @@
    formatted file that contains your private key. *cert_file* is a PEM formatted
    certificate chain file.
 
-   .. note::
-
-      This does not do any certificate verification.
+   .. warning::
+      This does not do any verification of the server's certificate.
 
    .. versionadded:: 2.0
 
diff --git a/Doc/library/urllib.rst b/Doc/library/urllib.rst
index eacde19..080d95d 100644
--- a/Doc/library/urllib.rst
+++ b/Doc/library/urllib.rst
@@ -23,6 +23,10 @@
 instead of filenames.  Some restrictions apply --- it can only open URLs for
 reading, and no seek operations are available.
 
+.. warning:: When opening HTTPS URLs, it is not attempted to validate the
+   server certificate.  Use at your own risk!
+
+
 High-level interface
 --------------------
 
diff --git a/Doc/library/urllib2.rst b/Doc/library/urllib2.rst
index 973c098..b977c4d 100644
--- a/Doc/library/urllib2.rst
+++ b/Doc/library/urllib2.rst
@@ -18,6 +18,9 @@
 URLs (mostly HTTP) in a complex world --- basic and digest authentication,
 redirections, cookies and more.
 
+.. warning:: When opening HTTPS (or FTPS) URLs, it is not attempted to
+   validate the server certificate.  Use at your own risk!
+
 The :mod:`urllib2` module defines the following functions: