diff --git a/cpp/CMakeLists.txt b/cpp/CMakeLists.txt
index 5910a3eab..5f941eef0 100644
--- a/cpp/CMakeLists.txt
+++ b/cpp/CMakeLists.txt
@@ -17,8 +17,8 @@
 cmake_minimum_required (VERSION 2.8)
 
 project (libphonenumber)
-set (libphonenumber_VERSION_MAJOR 3)
-set (libphonenumber_VERSION_MINOR 9)
+set (libphonenumber_VERSION_MAJOR 4)
+set (libphonenumber_VERSION_MINOR 0)
 
 # Helper functions dealing with finding libraries and programs this library
 # depends on.
diff --git a/debian/changelog b/debian/changelog
index 0480599c9..a892c7314 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+libphonenumber (4.0) lucid; urgency=low
+
+  * Version update.
+
+ -- Fredrik Roubert <roubert@google.com>  Wed, 12 Oct 2011 16:17:14 +0200
+
 libphonenumber (3.9) lucid; urgency=low
 
   * Version update.