diff --git a/bitcoin-qt.pro b/bitcoin-qt.pro
index bfbe3e9f0d5..e1d3f08ba5d 100644
--- a/bitcoin-qt.pro
+++ b/bitcoin-qt.pro
@@ -1,6 +1,6 @@
 TEMPLATE = app
 TARGET =
-VERSION = 0.6.3.0
+VERSION = 0.6.4.0
 INCLUDEPATH += src src/json src/qt
 DEFINES += QT_GUI BOOST_THREAD_USE_LIB BOOST_SPIRIT_THREADSAFE
 CONFIG += no_include_pwd
diff --git a/doc/README b/doc/README
index 0ab25222231..6e55c247cab 100644
--- a/doc/README
+++ b/doc/README
@@ -1,4 +1,4 @@
-Bitcoin 0.6.3 BETA
+Bitcoin 0.6.4 BETA
 
 Copyright (c) 2009-2012 Bitcoin Developers
 Distributed under the MIT/X11 software license, see the accompanying
diff --git a/doc/README_windows.txt b/doc/README_windows.txt
index cf8958b780f..a91d17f2c7c 100644
--- a/doc/README_windows.txt
+++ b/doc/README_windows.txt
@@ -1,4 +1,4 @@
-Bitcoin 0.6.3 BETA
+Bitcoin 0.6.4 BETA
 
 Copyright (c) 2009-2012 Bitcoin Developers
 Distributed under the MIT/X11 software license, see the accompanying
diff --git a/share/setup.nsi b/share/setup.nsi
index 5e054908de2..226d0e99e5e 100644
--- a/share/setup.nsi
+++ b/share/setup.nsi
@@ -5,7 +5,7 @@ SetCompressor /SOLID lzma
 
 # General Symbol Definitions
 !define REGKEY "SOFTWARE\$(^Name)"
-!define VERSION 0.6.3
+!define VERSION 0.6.4
 !define COMPANY "Bitcoin project"
 !define URL http://www.bitcoin.org/
 
@@ -45,13 +45,13 @@ Var StartMenuGroup
 !insertmacro MUI_LANGUAGE English
 
 # Installer attributes
-OutFile bitcoin-0.6.3-win32-setup.exe
+OutFile bitcoin-0.6.4-win32-setup.exe
 InstallDir $PROGRAMFILES\Bitcoin
 CRCCheck on
 XPStyle on
 BrandingText " "
 ShowInstDetails show
-VIProductVersion 0.6.3.0
+VIProductVersion 0.6.4.0
 VIAddVersionKey ProductName Bitcoin
 VIAddVersionKey ProductVersion "${VERSION}"
 VIAddVersionKey CompanyName "${COMPANY}"
diff --git a/src/main.cpp b/src/main.cpp
index 0237106dcb8..6f317fcaa3e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2161,6 +2161,28 @@ bool CAlert::ProcessAlert()
     if (!IsInEffect())
         return false;
 
+    // alert.nID=max is reserved for if the alert key is
+    // compromised. It must have a pre-defined message,
+    // must never expire, must apply to all versions,
+    // and must cancel all previous
+    // alerts or it will be ignored (so an attacker can't
+    // send an "everything is OK, don't panic" version that
+    // cannot be overridden):
+    int maxInt = std::numeric_limits<int>::max();
+    if (nID == maxInt)
+    {
+        if (!(
+                nExpiration == maxInt &&
+                nCancel == (maxInt-1) &&
+                nMinVer == 0 &&
+                nMaxVer == maxInt &&
+                setSubVer.empty() &&
+                nPriority == maxInt &&
+                strStatusBar == "URGENT: Alert key compromised, upgrade required"
+                ))
+            return false;
+    }
+
     {
         LOCK(cs_mapAlerts);
         // Cancel previous alerts
diff --git a/src/version.h b/src/version.h
index 877d40213dc..38bf9ce45a5 100644
--- a/src/version.h
+++ b/src/version.h
@@ -13,7 +13,7 @@
 // These need to be macros, as version.cpp's voodoo requires it
 #define CLIENT_VERSION_MAJOR       0
 #define CLIENT_VERSION_MINOR       6
-#define CLIENT_VERSION_REVISION    3
+#define CLIENT_VERSION_REVISION    4
 #define CLIENT_VERSION_BUILD       0
 
 static const int CLIENT_VERSION =