diff --git a/browser/config/mozconfigs/win32/debug b/browser/config/mozconfigs/win32/debug
index 4f6676db27d..e33e711c59d 100644
--- a/browser/config/mozconfigs/win32/debug
+++ b/browser/config/mozconfigs/win32/debug
@@ -7,7 +7,11 @@ export MOZILLA_OFFICIAL=1
 
 mk_add_options MOZ_MAKE_FLAGS=-j1
 
-. $topsrcdir/build/win32/mozconfig.vs2010
+if test "$PROCESSOR_ARCHITECTURE" = "AMD64" -o "$PROCESSOR_ARCHITEW6432" = "AMD64"; then
+  . $topsrcdir/build/win32/mozconfig.vs2010-win64
+else
+  . $topsrcdir/build/win32/mozconfig.vs2010
+fi
 
 # Package js shell.
 export MOZ_PACKAGE_JSSHELL=1
diff --git a/browser/config/mozconfigs/win32/l10n-mozconfig b/browser/config/mozconfigs/win32/l10n-mozconfig
index 41575360d98..75ccdfe256b 100644
--- a/browser/config/mozconfigs/win32/l10n-mozconfig
+++ b/browser/config/mozconfigs/win32/l10n-mozconfig
@@ -3,4 +3,8 @@ ac_add_options --enable-update-packaging
 ac_add_options --enable-official-branding
 ac_add_options --with-l10n-base=../../l10n-central
 
-. $topsrcdir/build/win32/mozconfig.vs2010
+if test "$PROCESSOR_ARCHITECTURE" = "AMD64" -o "$PROCESSOR_ARCHITEW6432" = "AMD64"; then
+  . $topsrcdir/build/win32/mozconfig.vs2010-win64
+else
+  . $topsrcdir/build/win32/mozconfig.vs2010
+fi
diff --git a/browser/config/mozconfigs/win32/nightly b/browser/config/mozconfigs/win32/nightly
index f4bbb3b1c7e..8e75c61ea2c 100644
--- a/browser/config/mozconfigs/win32/nightly
+++ b/browser/config/mozconfigs/win32/nightly
@@ -16,7 +16,11 @@ export MOZ_TELEMETRY_REPORTING=1
 
 mk_add_options MOZ_MAKE_FLAGS=-j1
 
-. $topsrcdir/build/win32/mozconfig.vs2010
+if test "$PROCESSOR_ARCHITECTURE" = "AMD64" -o "$PROCESSOR_ARCHITEW6432" = "AMD64"; then
+  . $topsrcdir/build/win32/mozconfig.vs2010-win64
+else
+  . $topsrcdir/build/win32/mozconfig.vs2010
+fi
 
 # Package js shell.
 export MOZ_PACKAGE_JSSHELL=1
diff --git a/browser/config/mozconfigs/win32/release b/browser/config/mozconfigs/win32/release
index 61091d62c1f..157abcc8663 100644
--- a/browser/config/mozconfigs/win32/release
+++ b/browser/config/mozconfigs/win32/release
@@ -12,7 +12,11 @@ export MOZILLA_OFFICIAL=1
 
 export MOZ_TELEMETRY_REPORTING=1
 
-. $topsrcdir/build/win32/mozconfig.vs2010
+if test "$PROCESSOR_ARCHITECTURE" = "AMD64" -o "$PROCESSOR_ARCHITEW6432" = "AMD64"; then
+  . $topsrcdir/build/win32/mozconfig.vs2010-win64
+else
+  . $topsrcdir/build/win32/mozconfig.vs2010
+fi
 
 # Package js shell.
 export MOZ_PACKAGE_JSSHELL=1