diff --git a/src/General/lib/$.coffee b/src/General/lib/$.coffee
index 11a6c6d57..083ce408b 100755
--- a/src/General/lib/$.coffee
+++ b/src/General/lib/$.coffee
@@ -178,7 +178,7 @@ $.off = (el, events, handler) ->
 
 $.event = (event, detail, root=d) ->
   <% if (type === 'userscript') { %>
-  if typeof cloneInto is 'function'
+  if detail? and typeof cloneInto is 'function'
     detail = cloneInto detail, document.defaultView
   <% } %>
   root.dispatchEvent new CustomEvent event, {bubbles: true, detail}
diff --git a/src/Miscellaneous/Fourchan.coffee b/src/Miscellaneous/Fourchan.coffee
index 982ec45d7..5d5159f51 100755
--- a/src/Miscellaneous/Fourchan.coffee
+++ b/src/Miscellaneous/Fourchan.coffee
@@ -21,7 +21,7 @@ Fourchan =
           if (!jsMath) return;
           if (jsMath.loaded) {
             // process one post
-            jsMath.ProcessBeforeShowing(document.getElementById('p' + e.detail));
+            jsMath.ProcessBeforeShowing(document.getElementById(e.detail));
           } else if (jsMath.Autoload && jsMath.Autoload.checked) {
             // load jsMath and process whole document
             jsMath.Autoload.Script.Push('ProcessBeforeShowing', [null]);
@@ -43,7 +43,7 @@ Fourchan =
   math: ->
     return if (@isClone and doc.contains @origin.nodes.root) or !$ '.math', @nodes.comment
     $.asap (=> doc.contains @nodes.post), =>
-      $.event 'jsmath', @ID, window
+      $.event 'jsmath', @nodes.post.id, window
   parseThread: (threadID, offset, limit) ->
     # Fix /sci/
     # Fix /g/