--- a/db/mork/src/morkConfig.h
+++ b/db/mork/src/morkConfig.h
@@ -67,17 +67,17 @@ void mork_fileflush(FILE * file);
 #define MORK_ENABLE_ZONE_ARENAS 1 /* using morkZone for pooling */
 
 //#define MORK_ENABLE_PROBE_MAPS 1 /* use smaller hash tables */
 
 #define MORK_BEAD_OVER_NODE_MAPS 1 /* use bead not node maps */
 
 /* ===== pooling ===== */
 
-#if defined(HAVE_64BIT_OS)
+#if defined(HAVE_64BIT_BUILD)
 #define MORK_CONFIG_ALIGN_8 1 /* must have 8 byte alignment */
 #else
 #define MORK_CONFIG_PTR_SIZE_4 1 /* sizeof(void*) == 4 */
 #endif
 
 // #define MORK_DEBUG_HEAP_STATS 1 /* analyze per-block heap usage */
 
 /* ===== ===== ===== ===== line characters ===== ===== ===== ===== */

--- a/mail/configure.in
+++ b/mail/configure.in
@@ -118,17 +118,17 @@ if test -n "$COMPILE_ENVIRONMENT" -a -n 
                 mkdir "ldap/sdks"
             fi
             mkdir "ldap/sdks/c-sdk"
         fi
         mkdir "ldap/sdks/c-sdk/ldap"
     fi
 
     ac_configure_args="$_SUBDIR_CONFIG_ARGS --prefix=$MOZ_BUILD_ROOT/dist --with-dist-prefix=$MOZ_BUILD_ROOT/dist --without-nss --with-mozilla"
-    if test -n "$HAVE_64BIT_OS"; then
+    if test -n "$HAVE_64BIT_BUILD"; then
         dnl A 64-bit OS was (auto-)detected: (explicitly) enable 64-bit support.
         ac_configure_args="$ac_configure_args --enable-64bit"
     fi
     if test -n "$LIBXUL_SDK"; then
         ac_configure_args="$ac_configure_args --with-nspr=$LIBXUL_DIST"
     fi
 
     dnl The cache file needs to be an absolute path to work properly.

--- a/mail/confvars.sh
+++ b/mail/confvars.sh
@@ -8,17 +8,17 @@ MOZ_APP_NAME=thunderbird
 MOZ_UPDATER=1
 MOZ_THUNDERBIRD=1
 MOZ_CHROME_FILE_FORMAT=omni
 MOZ_NO_ACTIVEX_SUPPORT=1
 MOZ_ACTIVEX_SCRIPTING_SUPPORT=
 MOZ_LDAP_XPCOM=1
 MOZ_COMPOSER=1
 if test "$OS_ARCH" = "WINNT"; then
-  if ! test "$HAVE_64BIT_OS"; then
+  if ! test "$HAVE_64BIT_BUILD"; then
     MOZ_VERIFY_MAR_SIGNATURE=1
     MOZ_MAINTENANCE_SERVICE=1
   fi
 fi
 
 MOZ_SAFE_BROWSING=1
 MOZ_MEDIA_NAVIGATOR=1
 MOZ_MORK=1

--- a/mail/installer/windows/nsis/defines.nsi.in
+++ b/mail/installer/windows/nsis/defines.nsi.in
@@ -32,18 +32,18 @@
 # Beta releases built with official branding from finding an existing install
 # of an official release and defaulting to its installation directory.
 !if "@PRE_RELEASE_SUFFIX@" != ""
 !define NO_INSTDIR_FROM_REG
 !endif
 
 # ARCH is used when it is necessary to differentiate the x64 registry keys from
 # the x86 registry keys (e.g. the uninstall registry key).
-#ifdef HAVE_64BIT_OS
-!define HAVE_64BIT_OS
+#ifdef HAVE_64BIT_BUILD
+!define HAVE_64BIT_BUILD
 !define ARCH "x64"
 !define MinSupportedVer "Microsoft Windows Vista x64"
 #else
 !define ARCH "x86"
 !define MinSupportedVer "Microsoft Windows XP SP2"
 #endif
 
 #ifdef MOZ_MAINTENANCE_SERVICE

--- a/mail/installer/windows/nsis/installer.nsi
+++ b/mail/installer/windows/nsis/installer.nsi
@@ -108,17 +108,17 @@ VIAddVersionKey "OriginalFilename" "setu
 !insertmacro InstallStartCleanupCommon
 !insertmacro LeaveDirectoryCommon
 !insertmacro LeaveOptionsCommon
 !insertmacro OnEndCommon
 !insertmacro PreDirectoryCommon
 
 Name "${BrandFullName}"
 OutFile "setup.exe"
-!ifdef HAVE_64BIT_OS
+!ifdef HAVE_64BIT_BUILD
   InstallDir "$PROGRAMFILES64\${BrandFullName}\"
 !else
   InstallDir "$PROGRAMFILES32\${BrandFullName}\"
 !endif
 ShowInstDetails nevershow
 
 ################################################################################
 # Modern User Interface - MUI

--- a/mail/installer/windows/nsis/maintenanceservice_installer.nsi
+++ b/mail/installer/windows/nsis/maintenanceservice_installer.nsi
@@ -70,19 +70,19 @@ OutFile "maintenanceservice_installer.ex
 ; Get installation folder from registry if available
 InstallDirRegKey HKLM "Software\Mozilla\MaintenanceService" ""
 
 SetOverwrite on
 
 !define MaintUninstallKey \
  "Software\Microsoft\Windows\CurrentVersion\Uninstall\MozillaMaintenanceService"
 
-; The HAVE_64BIT_OS define also means that we have an x64 build,
+; The HAVE_64BIT_BUILD define also means that we have an x64 build,
 ; not just an x64 OS.
-!ifdef HAVE_64BIT_OS
+!ifdef HAVE_64BIT_BUILD
   ; See below, we actually abort the install for x64 builds currently.
   InstallDir "$PROGRAMFILES64\${MaintFullName}\"
 !else
   InstallDir "$PROGRAMFILES32\${MaintFullName}\"
 !endif
 ShowUnInstDetails nevershow
 
 ################################################################################
@@ -115,17 +115,17 @@ ShowUnInstDetails nevershow
 BrandingText " "
 
 Function .onInit
   ; Remove the current exe directory from the search order.
   ; This only effects LoadLibrary calls and not implicitly loaded DLLs.
   System::Call 'kernel32::SetDllDirectoryW(w "")'
 
   SetSilent silent
-!ifdef HAVE_64BIT_OS
+!ifdef HAVE_64BIT_BUILD
   ; We plan to eventually enable 64bit native builds to use the maintenance
   ; service, but for the initial release, to reduce testing and development,
   ; 64-bit builds will not install the maintenanceservice.
   Abort
 !endif
 
   ; On Windows 2000 we do not install the maintenance service.
   ; We won't run this installer from the parent installer, but just in case 

--- a/mail/installer/windows/nsis/uninstaller.nsi
+++ b/mail/installer/windows/nsis/uninstaller.nsi
@@ -113,17 +113,17 @@ VIAddVersionKey "OriginalFilename" "help
 !insertmacro OnEndCommon
 !insertmacro UninstallOnInitCommon
 
 !insertmacro un.OnEndCommon
 !insertmacro un.UninstallUnOnInitCommon
 
 Name "${BrandFullName}"
 OutFile "helper.exe"
-!ifdef HAVE_64BIT_OS
+!ifdef HAVE_64BIT_BUILD
   InstallDir "$PROGRAMFILES64\${BrandFullName}\"
 !else
   InstallDir "$PROGRAMFILES32\${BrandFullName}\"
 !endif
 ShowUnInstDetails nevershow
 
 ################################################################################
 # Modern User Interface - MUI