diff --git a/Casks/thunderbird-beta.rb b/Casks/thunderbird-beta.rb
index 9b0210637..c7a48c5c6 100644
--- a/Casks/thunderbird-beta.rb
+++ b/Casks/thunderbird-beta.rb
@@ -1,6 +1,6 @@
 cask 'thunderbird-beta' do
-  version '45.0b2'
-  sha256 '84fbce6634afa0b300acea98bc532de3652b52ac5ab0b78c4c15b2f9cc1ce6e5'
+  version '45.0b4'
+  sha256 'e38876b00693d7860635ff9c6b126d10b379a58a8bf2597389d7fc797e40b718'
 
   url "https://download.mozilla.org/?product=thunderbird-#{version}&os=osx&lang=en-US"
   name 'Mozilla Thunderbird'