diff --git a/src/classes/Post.coffee b/src/classes/Post.coffee
index 62065b65a..4b78411f1 100644
--- a/src/classes/Post.coffee
+++ b/src/classes/Post.coffee
@@ -199,8 +199,8 @@ class Post
 
     $.extend file,
       url:     file.link.href
-      isImage: /\.(jpe?g|png|gif|bmp)$/i.test file.link.href
-      isVideo: /\.(webm|mp4)$/i.test file.link.href
+      isImage: $.isImage file.link.href
+      isVideo: $.isVideo file.link.href
     size  = +file.size.match(/[\d.]+/)[0]
     unit  = ['B', 'KB', 'MB', 'GB'].indexOf file.size.match(/\w+$/)[0]
     size *= 1024 while unit-- > 0
diff --git a/src/platform/$.coffee b/src/platform/$.coffee
index e0df4ecb3..dfceb3f87 100644
--- a/src/platform/$.coffee
+++ b/src/platform/$.coffee
@@ -490,6 +490,9 @@ $.unescape = (text) ->
   text.replace(/<[^>]*>/g, '').replace /&(amp|#039|quot|lt|gt|#44);/g, (c) ->
     (({'&amp;': '&', '&#039;': "'", '&quot;': '"', '&lt;': '<', '&gt;': '>', '&#44;': ','})[c])
 
+$.isImage = (url) -> /\.(jpe?g|png|gif|bmp)$/i.test url
+$.isVideo = (url) -> /\.(webm|mp4)$/i.test url
+
 $.engine = do ->
   return 'edge'   if /Edge\//.test navigator.userAgent
   return 'blink'  if /Chrome\//.test navigator.userAgent
diff --git a/src/site/SW.tinyboard.coffee b/src/site/SW.tinyboard.coffee
index c8c10ce63..4290193e3 100644
--- a/src/site/SW.tinyboard.coffee
+++ b/src/site/SW.tinyboard.coffee
@@ -218,7 +218,7 @@ SW.tinyboard =
       dimensions: info[0].match(/\d+x\d+/)?[0]
     if thumb
       $.extend file,
-        thumbURL:  if /\/static\//.test(thumb.src) and /\.(?:gif|jpe?g|png)$/.test(link.href) then link.href else thumb.src
+        thumbURL:  if /\/static\//.test(thumb.src) and $.isImage(link.href) then link.href else thumb.src
         isSpoiler: /^Spoiler/i.test(info[1] or '') or link.textContent is 'Spoiler Image'
     true