diff --git a/src/General/Build.Test.coffee b/src/General/Build.Test.coffee
index f2f7777f6..3cc2b4113 100644
--- a/src/General/Build.Test.coffee
+++ b/src/General/Build.Test.coffee
@@ -39,6 +39,8 @@ Build.Test =
       $.rmClass el, 'prettyprinted'
     for el in $$ 'pre[style=""]', root2
       el.removeAttribute 'style'
+    # XXX https://bugzilla.mozilla.org/show_bug.cgi?id=1021289
+    $('.fileInfo[data-md5]', root2)?.removeAttribute 'data-md5'
     textNodes = $.X './/text()', root2
     i = 0
     while (node = textNodes.snapshotItem i++)
diff --git a/src/General/Build/File.html b/src/General/Build/File.html
index de27d985c..ad6874f2f 100644
--- a/src/General/Build/File.html
+++ b/src/General/Build/File.html
@@ -1,7 +1,7 @@
 ?{file}{
   <div class="file" id="f${ID}">
   ?{boardID === "f"}{
-    <div class="fileInfo"><span class="fileText" id="fT${ID}">
+    <div class="fileInfo" data-md5="${file.MD5}"><span class="fileText" id="fT${ID}">
       File: 
       <a data-width="${file.width}" data-height="${file.height}" href="${fileURL}" target="_blank">${file.name}</a>
       -(${file.size}, ${file.dimensions}?{file.tag}{, ${file.tag}})
diff --git a/src/classes/Post.coffee b/src/classes/Post.coffee
index 7a8a13fe7..16f2995ce 100644
--- a/src/classes/Post.coffee
+++ b/src/classes/Post.coffee
@@ -199,6 +199,7 @@ class Post
       isVideo:    /webm$/i.test link.href
       dimensions: info[0].match(/\d+x\d+/)?[0]
       tag:        info[0].match(/,[^,]*, ([a-z]+)\)/i)?[1]
+      MD5:        fileText.dataset.md5
     size  = +@file.size.match(/[\d.]+/)[0]
     unit  = ['B', 'KB', 'MB', 'GB'].indexOf @file.size.match(/\w+$/)[0]
     size *= 1024 while unit-- > 0