diff --git a/extra/thunderbird/PKGBUILD b/extra/thunderbird/PKGBUILD
index cc8316bf2..57df116cb 100644
--- a/extra/thunderbird/PKGBUILD
+++ b/extra/thunderbird/PKGBUILD
@@ -16,7 +16,7 @@ highmem=1
 
 pkgname=thunderbird
 pkgver=45.1.0
-pkgrel=1
+pkgrel=2
 pkgdesc="Standalone mail and news reader from mozilla.org"
 arch=('i686' 'x86_64')
 license=('MPL' 'GPL' 'LGPL')
@@ -43,7 +43,7 @@ sha256sums=('8ae9ebe536895d69d99f412f2b3aba645b7dd839e520959330da13892d672309'
             '4d1e1ddabc9e975ed39f49e134559a29e01cd49439e358233f1ede43bf5a52bf'
             '2588c567fec88b44b65f0cd111e8769361c138d4c964310684f7bb80066f8f9f'
             'd1ccbaf0973615c57f7893355e5cd3a89efb4e91071d0ec376e429b50cf6ed19'
-            'e4ea8e6788163d9f8db8f1f40023db3ea0a1358f9a4510169f2d4c4fe6a887ed'
+            '8f9ee921896b939e36d089c8ff544bc2b0a8b56dd5a2b4f5e75a19a6e1849284'
             '59f40d8b2480aa67bf76f4f119826b6828a6a59cc040caf1ab5a6e19eef44c6e')
 
 # Google API keys (see http://www.chromium.org/developers/how-tos/api-keys)
diff --git a/extra/thunderbird/vendor.js b/extra/thunderbird/vendor.js
index 170b505a8..e1341de4e 100644
--- a/extra/thunderbird/vendor.js
+++ b/extra/thunderbird/vendor.js
@@ -7,3 +7,6 @@ pref("mail.shell.checkDefaultMail", false);
 // Don't disable our bundled extensions in the application directory
 pref("extensions.autoDisableScopes", 11);
 pref("extensions.shownSelectionUI", true);
+
+// https://bugzilla.mozilla.org/show_bug.cgi?id=1245783
+pref("javascript.options.ion", false);