diff --git a/filter/mathjaxloader/db/upgrade.php b/filter/mathjaxloader/db/upgrade.php
index cfc9ea79e47b5..a16cbf1d068d4 100644
--- a/filter/mathjaxloader/db/upgrade.php
+++ b/filter/mathjaxloader/db/upgrade.php
@@ -31,6 +31,8 @@
 function xmldb_filter_mathjaxloader_upgrade($oldversion) {
     global $CFG, $DB;
 
+    require_once($CFG->dirroot . '/filter/mathjaxloader/db/upgradelib.php');
+
     $dbman = $DB->get_manager();
 
     if ($oldversion < 2014081100) {
@@ -157,6 +159,14 @@ function xmldb_filter_mathjaxloader_upgrade($oldversion) {
     }
     // Automatically generated Moodle v3.2.0 release upgrade line.
     // Put any upgrade step following this.
+    if ($oldversion < 2017040300) {
+
+        $httpsurl = get_config('filter_mathjaxloader', 'httpsurl');
+        $newcdnurl = filter_mathjaxloader_upgrade_cdn_cloudflare($httpsurl, false);
+
+        set_config('httpsurl', $newcdnurl, 'filter_mathjaxloader');
+        upgrade_plugin_savepoint(true, 2017040300, 'filter', 'mathjaxloader');
+    }
 
     return true;
 }
diff --git a/filter/mathjaxloader/db/upgradelib.php b/filter/mathjaxloader/db/upgradelib.php
new file mode 100644
index 0000000000000..295d4b3d9a854
--- /dev/null
+++ b/filter/mathjaxloader/db/upgradelib.php
@@ -0,0 +1,66 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Random functions for mathjax upgrades.
+ *
+ * @package    filter_mathjaxloader
+ * @copyright  2017 Damyon Wiese (damyon@moodle.com)
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * This function takes an existing mathjax url and, if it was using the standard mathjax cdn,
+ * upgrades it to use the cloudflare matchjax cdn (because the standard one is shutting down).
+ * @param string $mathjaxurl - The current url.
+ * @param boolean $httponly - Use http instead of https - really only for 3.1 upgrades.
+ * @return string The new url.
+ */
+function filter_mathjaxloader_upgrade_cdn_cloudflare($mathjaxurl, $httponly = false) {
+    $newcdnurl = $mathjaxurl;
+    $cdnroot = 'https://cdn.mathjax.org/mathjax/';
+    if ($httponly) {
+        $cdnroot = 'http://cdn.mathjax.org/mathjax/';
+    }
+    $usingcdn = strpos($mathjaxurl, $cdnroot) === 0;
+    if ($usingcdn) {
+        $majorversion = substr($mathjaxurl, strlen($cdnroot), 3);
+        $latestversion = '2.7.0';
+        if ($majorversion == '2.6') {
+            $latestversion = '2.6.1';
+        } else if ($majorversion == '2.5') {
+            $latestversion = '2.5.3';
+        }
+
+        $offset = strpos($mathjaxurl, '/', strlen($cdnroot));
+        if ($offset === false) {
+            return $newcdnurl;
+        }
+
+        $endofurl = substr($mathjaxurl, $offset + 1);
+
+        $newcdnbase = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/';
+        if ($httponly) {
+            $newcdnbase = 'http://cdnjs.cloudflare.com/ajax/libs/mathjax/';
+        }
+
+        $newcdnurl = $newcdnbase . $latestversion . '/' . $endofurl;
+    }
+
+    return $newcdnurl;
+}
diff --git a/filter/mathjaxloader/tests/upgradelib_test.php b/filter/mathjaxloader/tests/upgradelib_test.php
new file mode 100644
index 0000000000000..01d99088671a6
--- /dev/null
+++ b/filter/mathjaxloader/tests/upgradelib_test.php
@@ -0,0 +1,91 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Unit test for the upgrade MathJax code.
+ *
+ * @package    filter_mathjaxloader
+ * @copyright  2017 Damyon Wiese
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+require_once($CFG->dirroot . '/filter/mathjaxloader/db/upgradelib.php');
+
+/**
+ * Unit test for the upgrade MathJax code.
+ *
+ * Test the functions in upgradelib.php
+ *
+ * @copyright  2017 Damyon Wiese
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class filter_mathjax_upgradelib_testcase extends advanced_testcase {
+
+    public function test_upgradelib() {
+        $current = 'https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?...';
+        $expected = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        $current = 'http://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?...';
+        $expected = 'http://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current, true));
+
+        $current = 'http://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?...';
+        $expected = 'http://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current, false));
+
+        $current = 'https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?...';
+        $expected = 'https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current, true));
+
+        $current = 'https://cdn.mathjax.org/mathjax/2.6-latest/MathJax.js?...';
+        $expected = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.6.1/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        $current = 'https://cdn.mathjax.org/mathjax/2.5-latest/MathJax.js?...';
+        $expected = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.5.3/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        // Dont touch non https links.
+        $current = 'http://cdn.mathjax.org/mathjax/2.5-latest/MathJax.js?...';
+        $expected = 'http://cdn.mathjax.org/mathjax/2.5-latest/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        // Dont touch non local links.
+        $current = 'https://mylocalmirror/mathjax/2.7-latest/MathJax.js?...';
+        $expected = 'https://mylocalmirror/mathjax/2.7-latest/MathJax.js?...';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        // Try some unexpected things.
+        $current = '';
+        $expected = '';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        // Try some unexpected things.
+        $current = 'https://cdn.mathjax.org/mathjax/2.7-latest/MathJax.js';
+        $expected = 'https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+
+        // Try some unexpected things.
+        $current = 'https://cdn.mathjax.org/mathjax/2.7-latest';
+        $expected = 'https://cdn.mathjax.org/mathjax/2.7-latest';
+        $this->assertEquals($expected, filter_mathjaxloader_upgrade_cdn_cloudflare($current));
+    }
+}
+
diff --git a/filter/mathjaxloader/version.php b/filter/mathjaxloader/version.php
index 69b63b3e32c55..062f3244dc438 100644
--- a/filter/mathjaxloader/version.php
+++ b/filter/mathjaxloader/version.php
@@ -24,6 +24,6 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version  = 2016120500;
+$plugin->version  = 2017040300;
 $plugin->requires = 2016112900;  // Requires this Moodle version.
 $plugin->component= 'filter_mathjaxloader';