diff --git a/Gruntfile.js b/Gruntfile.js
index 4f970bd9..5ff2f110 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -125,6 +125,14 @@ module.exports = function(grunt) {
                 'textsecure-service-ca.whispersystems.org:4433').replace(
                 /whispersystems-textsecure-attachments-staging.s3.amazonaws.com/g,
                 'whispersystems-textsecure-attachments.s3.amazonaws.com');
+            } else if (srcpath.match('expire.js')) {
+              var gitinfo = grunt.config.get('gitinfo');
+              var commited = gitinfo.local.branch.current.lastCommitTime;
+              var time = Date.parse(commited) + 1000 * 60 * 60 * 24 * 90;
+              return content.replace(
+                /var BUILD_EXPIRATION = 0/,
+                "var BUILD_EXPIRATION = " + time
+              );
             } else {
               return content;
             }
@@ -157,7 +165,7 @@ module.exports = function(grunt) {
       },
       dist: {
         files: ['<%= dist.src %>', '<%= dist.res %>'],
-        tasks: ['copy']
+        tasks: ['copy_dist']
       },
       scripts: {
         files: ['<%= jshint.files %>', './js/**/*.js'],
@@ -198,7 +206,8 @@ module.exports = function(grunt) {
       'tx-pull': {
         cmd: 'tx pull'
       }
-    }
+    },
+    gitinfo: {} // to be populated by grunt gitinfo
   });
 
   Object.keys(grunt.config.get('pkg').devDependencies).forEach(function(key) {
@@ -232,6 +241,7 @@ module.exports = function(grunt) {
   grunt.registerTask('tx', ['exec:tx-pull', 'locale-patch']);
   grunt.registerTask('dev', ['default', 'connect', 'watch']);
   grunt.registerTask('test', ['jshint', 'jscs', 'connect', 'saucelabs-mocha']);
-  grunt.registerTask('default', ['concat', 'sass', 'copy']);
+  grunt.registerTask('copy_dist', ['gitinfo', 'copy']);
+  grunt.registerTask('default', ['concat', 'sass', 'copy_dist']);
 
 };
diff --git a/background.html b/background.html
index a3817dce..2f845aea 100644
--- a/background.html
+++ b/background.html
@@ -382,6 +382,7 @@
   <script type='text/javascript' src='js/models/conversations.js'></script>
 
   <script type='text/javascript' src='js/chromium.js'></script>
+  <script type='text/javascript' src='js/expire.js'></script>
   <script type='text/javascript' src='js/conversation_controller.js'></script>
   <script type='text/javascript' src='js/panel_controller.js'></script>
   <script type='text/javascript' src='js/emoji_util.js'></script>
diff --git a/js/expire.js b/js/expire.js
new file mode 100644
index 00000000..639aeae8
--- /dev/null
+++ b/js/expire.js
@@ -0,0 +1,10 @@
+;(function() {
+    'use strict';
+    var BUILD_EXPIRATION = 0;
+
+    window.extension = window.extension || {};
+
+    extension.expired = function() {
+      return (BUILD_EXPIRATION && Date.now() > BUILD_EXPIRATION);
+    };
+})();
diff --git a/package.json b/package.json
index 77e4da7c..a5bf999a 100644
--- a/package.json
+++ b/package.json
@@ -13,6 +13,7 @@
     "grunt-contrib-sass": "^0.8.1",
     "grunt-contrib-watch": "^0.6.1",
     "grunt-exec": "^0.4.6",
+    "grunt-gitinfo": "^0.1.7",
     "grunt-jscs": "^1.1.0",
     "grunt-preen": "^1.0.0",
     "grunt-saucelabs": "^8.3.3"