diff --git a/CHANGELOG.md b/CHANGELOG.md
index fff40b931..5706e6b60 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,9 @@
 
 ### v1.13.15
 
+**v1.13.15.9** *(2018-02-09)* - [[Userscript](https://raw.githubusercontent.com/ccd0/4chan-x/1.13.15.9/builds/4chan-X-noupdate.user.js)] [[Chrome extension](https://raw.githubusercontent.com/ccd0/4chan-x/1.13.15.9/builds/4chan-X-noupdate.crx)]
+- Fix 404 redirection on error pages without doctype. #1811
+
 **v1.13.15.8** *(2018-02-01)* - [[Userscript](https://raw.githubusercontent.com/ccd0/4chan-x/1.13.15.8/builds/4chan-X-noupdate.user.js)] [[Chrome extension](https://raw.githubusercontent.com/ccd0/4chan-x/1.13.15.8/builds/4chan-X-noupdate.crx)]
 - Captcha bypass cookie does not work for starting threads. Updating to treat this case correctly.
 
diff --git a/builds/4chan-X-beta.crx b/builds/4chan-X-beta.crx
index 85c6aaf4f..35e9a3081 100644
Binary files a/builds/4chan-X-beta.crx and b/builds/4chan-X-beta.crx differ
diff --git a/builds/4chan-X-beta.meta.js b/builds/4chan-X-beta.meta.js
index 067cc799d..2c58eba7b 100644
--- a/builds/4chan-X-beta.meta.js
+++ b/builds/4chan-X-beta.meta.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         4chan X beta
-// @version      1.13.15.8
+// @version      1.13.15.9
 // @minGMVer     1.14
 // @minFFVer     26
 // @namespace    4chan-X
diff --git a/builds/4chan-X-beta.user.js b/builds/4chan-X-beta.user.js
index 4874b4fe9..338137f9d 100644
--- a/builds/4chan-X-beta.user.js
+++ b/builds/4chan-X-beta.user.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         4chan X beta
-// @version      1.13.15.8
+// @version      1.13.15.9
 // @minGMVer     1.14
 // @minFFVer     26
 // @namespace    4chan-X
@@ -159,7 +159,7 @@ docSet = function() {
 };
 
 g = {
-  VERSION:   '1.13.15.8',
+  VERSION:   '1.13.15.9',
   NAMESPACE: '4chan X.',
   boards:    {}
 };
@@ -24627,9 +24627,6 @@ Main = (function() {
           return;
         }
       } catch (_error) {}
-      if (location.hostname === 'boards.4chan.org' && d.documentElement && !d.doctype) {
-        return;
-      }
       if (doc && $.hasClass(doc, 'fourchan-x')) {
         return;
       }
@@ -24944,7 +24941,7 @@ Main = (function() {
         });
         return;
       }
-      if ((ref1 = d.title) === '4chan - Temporarily Offline' || ref1 === '4chan - 404 Not Found') {
+      if ((ref1 = d.title) === '4chan - Temporarily Offline' || ref1 === '4chan - 404 Not Found' || ref1 === 'MathJax Equation Source') {
         return;
       }
       if (((ref2 = g.VIEW) === 'index' || ref2 === 'thread') && !$('.board + *')) {
@@ -25137,7 +25134,7 @@ Main = (function() {
     isThisPageLegit: function() {
       var ref;
       if (!('thisPageIsLegit' in Main)) {
-        Main.thisPageIsLegit = location.hostname === 'boards.4chan.org' && !$('link[href*="favicon-status.ico"]', d.head) && ((ref = d.title) !== '4chan - Temporarily Offline' && ref !== '4chan - Error' && ref !== '504 Gateway Time-out');
+        Main.thisPageIsLegit = location.hostname === 'boards.4chan.org' && !$('link[href*="favicon-status.ico"]', d.head) && ((ref = d.title) !== '4chan - Temporarily Offline' && ref !== '4chan - Error' && ref !== '504 Gateway Time-out' && ref !== 'MathJax Equation Source');
       }
       return Main.thisPageIsLegit;
     },
diff --git a/builds/4chan-X-noupdate.crx b/builds/4chan-X-noupdate.crx
index 950fad9b1..5f621ff97 100644
Binary files a/builds/4chan-X-noupdate.crx and b/builds/4chan-X-noupdate.crx differ
diff --git a/builds/4chan-X-noupdate.user.js b/builds/4chan-X-noupdate.user.js
index a4fe82c5b..2e03acee4 100644
--- a/builds/4chan-X-noupdate.user.js
+++ b/builds/4chan-X-noupdate.user.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         4chan X
-// @version      1.13.15.8
+// @version      1.13.15.9
 // @minGMVer     1.14
 // @minFFVer     26
 // @namespace    4chan-X
@@ -159,7 +159,7 @@ docSet = function() {
 };
 
 g = {
-  VERSION:   '1.13.15.8',
+  VERSION:   '1.13.15.9',
   NAMESPACE: '4chan X.',
   boards:    {}
 };
@@ -24627,9 +24627,6 @@ Main = (function() {
           return;
         }
       } catch (_error) {}
-      if (location.hostname === 'boards.4chan.org' && d.documentElement && !d.doctype) {
-        return;
-      }
       if (doc && $.hasClass(doc, 'fourchan-x')) {
         return;
       }
@@ -24944,7 +24941,7 @@ Main = (function() {
         });
         return;
       }
-      if ((ref1 = d.title) === '4chan - Temporarily Offline' || ref1 === '4chan - 404 Not Found') {
+      if ((ref1 = d.title) === '4chan - Temporarily Offline' || ref1 === '4chan - 404 Not Found' || ref1 === 'MathJax Equation Source') {
         return;
       }
       if (((ref2 = g.VIEW) === 'index' || ref2 === 'thread') && !$('.board + *')) {
@@ -25137,7 +25134,7 @@ Main = (function() {
     isThisPageLegit: function() {
       var ref;
       if (!('thisPageIsLegit' in Main)) {
-        Main.thisPageIsLegit = location.hostname === 'boards.4chan.org' && !$('link[href*="favicon-status.ico"]', d.head) && ((ref = d.title) !== '4chan - Temporarily Offline' && ref !== '4chan - Error' && ref !== '504 Gateway Time-out');
+        Main.thisPageIsLegit = location.hostname === 'boards.4chan.org' && !$('link[href*="favicon-status.ico"]', d.head) && ((ref = d.title) !== '4chan - Temporarily Offline' && ref !== '4chan - Error' && ref !== '504 Gateway Time-out' && ref !== 'MathJax Equation Source');
       }
       return Main.thisPageIsLegit;
     },
diff --git a/builds/4chan-X.crx b/builds/4chan-X.crx
index b66872c19..b2899352e 100644
Binary files a/builds/4chan-X.crx and b/builds/4chan-X.crx differ
diff --git a/builds/4chan-X.meta.js b/builds/4chan-X.meta.js
index ad63d999a..7dce32a28 100644
--- a/builds/4chan-X.meta.js
+++ b/builds/4chan-X.meta.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         4chan X
-// @version      1.13.15.8
+// @version      1.13.15.9
 // @minGMVer     1.14
 // @minFFVer     26
 // @namespace    4chan-X
diff --git a/builds/4chan-X.user.js b/builds/4chan-X.user.js
index 0bf105785..f42c8effa 100644
--- a/builds/4chan-X.user.js
+++ b/builds/4chan-X.user.js
@@ -1,6 +1,6 @@
 // ==UserScript==
 // @name         4chan X
-// @version      1.13.15.8
+// @version      1.13.15.9
 // @minGMVer     1.14
 // @minFFVer     26
 // @namespace    4chan-X
@@ -159,7 +159,7 @@ docSet = function() {
 };
 
 g = {
-  VERSION:   '1.13.15.8',
+  VERSION:   '1.13.15.9',
   NAMESPACE: '4chan X.',
   boards:    {}
 };
@@ -24627,9 +24627,6 @@ Main = (function() {
           return;
         }
       } catch (_error) {}
-      if (location.hostname === 'boards.4chan.org' && d.documentElement && !d.doctype) {
-        return;
-      }
       if (doc && $.hasClass(doc, 'fourchan-x')) {
         return;
       }
@@ -24944,7 +24941,7 @@ Main = (function() {
         });
         return;
       }
-      if ((ref1 = d.title) === '4chan - Temporarily Offline' || ref1 === '4chan - 404 Not Found') {
+      if ((ref1 = d.title) === '4chan - Temporarily Offline' || ref1 === '4chan - 404 Not Found' || ref1 === 'MathJax Equation Source') {
         return;
       }
       if (((ref2 = g.VIEW) === 'index' || ref2 === 'thread') && !$('.board + *')) {
@@ -25137,7 +25134,7 @@ Main = (function() {
     isThisPageLegit: function() {
       var ref;
       if (!('thisPageIsLegit' in Main)) {
-        Main.thisPageIsLegit = location.hostname === 'boards.4chan.org' && !$('link[href*="favicon-status.ico"]', d.head) && ((ref = d.title) !== '4chan - Temporarily Offline' && ref !== '4chan - Error' && ref !== '504 Gateway Time-out');
+        Main.thisPageIsLegit = location.hostname === 'boards.4chan.org' && !$('link[href*="favicon-status.ico"]', d.head) && ((ref = d.title) !== '4chan - Temporarily Offline' && ref !== '4chan - Error' && ref !== '504 Gateway Time-out' && ref !== 'MathJax Equation Source');
       }
       return Main.thisPageIsLegit;
     },
diff --git a/builds/4chan-X.zip b/builds/4chan-X.zip
index 2680ea78a..92e39e11c 100644
Binary files a/builds/4chan-X.zip and b/builds/4chan-X.zip differ
diff --git a/builds/updates-beta.json b/builds/updates-beta.json
index ba0cb72e1..bf195a73a 100644
--- a/builds/updates-beta.json
+++ b/builds/updates-beta.json
@@ -3,7 +3,7 @@
     "4chan-x@4chan-x.net": {
       "updates": [
         {
-          "version": "1.13.15.8",
+          "version": "1.13.15.9",
           "update_link": "https://www.4chan-x.net/builds/4chan-X-beta.crx"
         }
       ]
diff --git a/builds/updates-beta.xml b/builds/updates-beta.xml
index 6b2acc0d3..e14ec4a97 100644
--- a/builds/updates-beta.xml
+++ b/builds/updates-beta.xml
@@ -1,7 +1,7 @@
 <?xml version='1.0' encoding='UTF-8'?>
 <gupdate xmlns='http://www.google.com/update2/response' protocol='2.0'>
   <app appid='lacclbnghgdicfifcamcmcnilckjamag'>
-    <updatecheck codebase='https://www.4chan-x.net/builds/4chan-X-beta.crx' version='1.13.15.8' />
+    <updatecheck codebase='https://www.4chan-x.net/builds/4chan-X-beta.crx' version='1.13.15.9' />
   </app>
 </gupdate>
 
diff --git a/builds/updates.json b/builds/updates.json
index 160a02f6d..320e30249 100644
--- a/builds/updates.json
+++ b/builds/updates.json
@@ -3,7 +3,7 @@
     "4chan-x@4chan-x.net": {
       "updates": [
         {
-          "version": "1.13.15.8",
+          "version": "1.13.15.9",
           "update_link": "https://www.4chan-x.net/builds/4chan-X.crx"
         }
       ]
diff --git a/builds/updates.xml b/builds/updates.xml
index 7b207f222..b10fb2064 100644
--- a/builds/updates.xml
+++ b/builds/updates.xml
@@ -1,7 +1,7 @@
 <?xml version='1.0' encoding='UTF-8'?>
 <gupdate xmlns='http://www.google.com/update2/response' protocol='2.0'>
   <app appid='lacclbnghgdicfifcamcmcnilckjamag'>
-    <updatecheck codebase='https://www.4chan-x.net/builds/4chan-X.crx' version='1.13.15.8' />
+    <updatecheck codebase='https://www.4chan-x.net/builds/4chan-X.crx' version='1.13.15.9' />
   </app>
 </gupdate>
 
diff --git a/version.json b/version.json
index ba89a2452..e004fb8eb 100644
--- a/version.json
+++ b/version.json
@@ -1,4 +1,4 @@
 {
-  "version": "1.13.15.8",
-  "date": "2018-02-01T04:29:02.005Z"
+  "version": "1.13.15.9",
+  "date": "2018-02-09T18:06:15.009Z"
 }
\ No newline at end of file