diff --git a/ipaddress.py b/ipaddress.py
index f2d0766..0009e9a 100644
--- a/ipaddress.py
+++ b/ipaddress.py
@@ -1686,11 +1686,11 @@ class _IPv4Constants(object):
     _private_networks = [
         IPv4Network('0.0.0.0/8'),
         IPv4Network('10.0.0.0/8'),
+        IPv4Network('100.64.0.0/10'),
         IPv4Network('127.0.0.0/8'),
         IPv4Network('169.254.0.0/16'),
         IPv4Network('172.16.0.0/12'),
-        IPv4Network('192.0.0.0/29'),
-        IPv4Network('192.0.0.170/31'),
+        IPv4Network('192.0.0.0/24'),
         IPv4Network('192.0.2.0/24'),
         IPv4Network('192.168.0.0/16'),
         IPv4Network('198.18.0.0/15'),