diff --git a/src/Monitoring/ThreadWatcher.coffee b/src/Monitoring/ThreadWatcher.coffee
index 5c9089556..94a9b987d 100644
--- a/src/Monitoring/ThreadWatcher.coffee
+++ b/src/Monitoring/ThreadWatcher.coffee
@@ -150,7 +150,7 @@ ThreadWatcher =
       {db}    = ThreadWatcher
       boardID = g.BOARD.ID
       nKilled = 0
-      for threadID, data of db.data.boards[boardID] when not data?.isDead and "#{boardID}.#{threadID}" not in e.detail.threads
+      for threadID, data of db.data[Site.hostname].boards[boardID] when not data?.isDead and "#{boardID}.#{threadID}" not in e.detail.threads
         # Don't prune threads that have yet to appear in index.
         continue unless e.detail.threads.some (fullID) -> +fullID.split('.')[1] > threadID
         nKilled++
@@ -188,7 +188,7 @@ ThreadWatcher =
     {db} = ThreadWatcher
     interval = if ThreadWatcher.unreadEnabled and Conf['Show Unread Count'] then 5 * $.MINUTE else 2 * $.HOUR
     now = Date.now()
-    unless now - interval < (db.data.lastChecked or 0) <= now or d.hidden or not d.hasFocus()
+    unless now - interval < (db.data[Site.hostname].lastChecked or 0) <= now or d.hidden or not d.hasFocus()
       ThreadWatcher.fetchAllStatus()
       db.setLastChecked()
     ThreadWatcher.timeout = setTimeout ThreadWatcher.fetchAuto, interval
@@ -288,7 +288,7 @@ ThreadWatcher =
 
   getAll: ->
     all = []
-    for boardID, threads of ThreadWatcher.db.data.boards
+    for boardID, threads of ThreadWatcher.db.data[Site.hostname].boards
       if Conf['Current Board'] and boardID isnt g.BOARD.ID
         continue
       for threadID, data of threads when data and typeof data is 'object'
diff --git a/src/classes/DataBoard.coffee b/src/classes/DataBoard.coffee
index 479dabb2c..ac1e2092a 100644
--- a/src/classes/DataBoard.coffee
+++ b/src/classes/DataBoard.coffee
@@ -13,11 +13,8 @@ class DataBoard
       @sync = sync
     $.on d, '4chanXInitFinished', init
 
-  initData: (@allData) ->
-    if Site.hostname is '4chan.org' and @allData.boards
-      @data = @allData
-    else
-      @data = (@allData[Site.hostname] or= boards: {})
+  initData: (@data) ->
+    @data[Site.hostname] or= boards: {}
 
   changes: []
 
@@ -26,72 +23,75 @@ class DataBoard
     @changes.push change
     $.get @key, {boards: {}}, (items) =>
       return unless @changes.length
-      needSync = ((items[@key].version or 0) > (@allData.version or 0))
+      needSync = ((items[@key].version or 0) > (@data.version or 0))
       if needSync
         @initData items[@key]
         change() for change in @changes
       @changes = []
-      @allData.version = (@allData.version or 0) + 1
-      $.set @key, @allData, =>
+      @data.version = (@data.version or 0) + 1
+      $.set @key, @data, =>
         @sync?() if needSync
         cb?()
 
   forceSync: (cb) ->
     $.get @key, {boards: {}}, (items) =>
-      if (items[@key].version or 0) > (@allData.version or 0)
+      if (items[@key].version or 0) > (@data.version or 0)
         @initData items[@key]
         change() for change in @changes
         @sync?()
       cb?()
 
-  delete: ({boardID, threadID, postID}) ->
+  delete: ({siteID, boardID, threadID, postID}) ->
+    siteID or= Site.hostname
     @save =>
       if postID
-        return unless @data.boards[boardID]?[threadID]
-        delete @data.boards[boardID][threadID][postID]
-        @deleteIfEmpty {boardID, threadID}
+        return unless @data[siteID].boards[boardID]?[threadID]
+        delete @data[siteID].boards[boardID][threadID][postID]
+        @deleteIfEmpty {siteID, boardID, threadID}
       else if threadID
-        return unless @data.boards[boardID]
-        delete @data.boards[boardID][threadID]
-        @deleteIfEmpty {boardID}
+        return unless @data[siteID].boards[boardID]
+        delete @data[siteID].boards[boardID][threadID]
+        @deleteIfEmpty {siteID, boardID}
       else
-        delete @data.boards[boardID]
+        delete @data[siteID].boards[boardID]
 
-  deleteIfEmpty: ({boardID, threadID}) ->
+  deleteIfEmpty: ({siteID, boardID, threadID}) ->
     if threadID
-      unless Object.keys(@data.boards[boardID][threadID]).length
-        delete @data.boards[boardID][threadID]
-        @deleteIfEmpty {boardID}
-    else unless Object.keys(@data.boards[boardID]).length
-      delete @data.boards[boardID]
+      unless Object.keys(@data[siteID].boards[boardID][threadID]).length
+        delete @data[siteID].boards[boardID][threadID]
+        @deleteIfEmpty {siteID, boardID}
+    else unless Object.keys(@data[siteID].boards[boardID]).length
+      delete @data[siteID].boards[boardID]
 
   set: (data, cb) ->
     @save =>
       @setUnsafe data
     , cb
 
-  setUnsafe: ({boardID, threadID, postID, val}) ->
+  setUnsafe: ({siteID, boardID, threadID, postID, val}) ->
+    siteID or= Site.hostname
     if postID isnt undefined
-      ((@data.boards[boardID] or= {})[threadID] or= {})[postID] = val
+      ((@data[siteID].boards[boardID] or= {})[threadID] or= {})[postID] = val
     else if threadID isnt undefined
-      (@data.boards[boardID] or= {})[threadID] = val
+      (@data[siteID].boards[boardID] or= {})[threadID] = val
     else
-      @data.boards[boardID] = val
+      @data[siteID].boards[boardID] = val
 
-  extend: ({boardID, threadID, postID, val, rm}, cb) ->
+  extend: ({siteID, boardID, threadID, postID, val, rm}, cb) ->
     @save =>
-      oldVal = @get {boardID, threadID, postID, val: {}}
+      oldVal = @get {siteID, boardID, threadID, postID, val: {}}
       delete oldVal[key] for key in rm or []
       $.extend oldVal, val
-      @setUnsafe {boardID, threadID, postID, val: oldVal}
+      @setUnsafe {siteID, boardID, threadID, postID, val: oldVal}
     , cb
 
-  setLastChecked: ->
+  setLastChecked: (siteID=Site.hostname) ->
     @save =>
-      @data.lastChecked = Date.now()
+      @data[siteID].lastChecked = Date.now()
 
-  get: ({boardID, threadID, postID, defaultValue}) ->
-    if board = @data.boards[boardID]
+  get: ({siteID, boardID, threadID, postID, defaultValue}) ->
+    siteID or= Site.hostname
+    if board = @data[siteID].boards[boardID]
       unless threadID?
         if postID?
           for ID, thread in board
@@ -110,14 +110,15 @@ class DataBoard
   clean: ->
     # XXX not yet multisite ready
     return unless Site.software is 'yotsuba'
+    siteID = Site.hostname
 
-    for boardID, val of @data.boards
-      @deleteIfEmpty {boardID}
+    for boardID, val of @data[siteID].boards
+      @deleteIfEmpty {siteID, boardID}
 
     now = Date.now()
-    unless now - 2 * $.HOUR < (@data.lastChecked or 0) <= now
-      @data.lastChecked = now
-      for boardID of @data.boards
+    unless now - 2 * $.HOUR < (@data[siteID].lastChecked or 0) <= now
+      @data[siteID].lastChecked = now
+      for boardID of @data[siteID].boards
         @ajaxClean boardID
     return
 
@@ -130,7 +131,8 @@ class DataBoard
         @ajaxCleanParse boardID, response1, e2.target.response
 
   ajaxCleanParse: (boardID, response1, response2) ->
-    return if not (board = @data.boards[boardID])
+    siteID = Site.hostname
+    return if not (board = @data[siteID].boards[boardID])
     threads = {}
     if response1
       for page in response1
@@ -140,11 +142,11 @@ class DataBoard
     if response2
       for ID in response2
         threads[ID] = board[ID] if ID of board
-    @data.boards[boardID] = threads
-    @deleteIfEmpty {boardID}
+    @data[siteID].boards[boardID] = threads
+    @deleteIfEmpty {siteID, boardID}
     $.set @key, @allData
 
   onSync: (data) =>
-    return unless (data.version or 0) > (@allData.version or 0)
+    return unless (data.version or 0) > (@data.version or 0)
     @initData data
     @sync?()