diff --git a/XMonad/Actions/TreeSelect.hs b/XMonad/Actions/TreeSelect.hs
index 4d7ca970..f243787a 100644
--- a/XMonad/Actions/TreeSelect.hs
+++ b/XMonad/Actions/TreeSelect.hs
@@ -317,7 +317,9 @@ treeselectAt conf@TSConfig{..} zipper hist = withDisplay $ \display -> do
         set_colormap attributes colormap
         set_background_pixel attributes ts_background
         set_border_pixel attributes 0
-        createWindow display rootw rect_x rect_y rect_width rect_height 0 (visualInfo_depth vinfo) inputOutput (visualInfo_visual vinfo) (cWColormap .|. cWBorderPixel .|. cWBackPixel) attributes
+        w <- createWindow display rootw rect_x rect_y rect_width rect_height 0 (visualInfo_depth vinfo) inputOutput (visualInfo_visual vinfo) (cWColormap .|. cWBorderPixel .|. cWBackPixel) attributes
+        setClassHint display w (ClassHint "xmonad-tree_select" "xmonad")
+        pure w
 
     liftIO $ do
         -- TODO: move below?
diff --git a/XMonad/Layout/Decoration.hs b/XMonad/Layout/Decoration.hs
index bd4fbc8c..54c0a25a 100644
--- a/XMonad/Layout/Decoration.hs
+++ b/XMonad/Layout/Decoration.hs
@@ -377,8 +377,12 @@ createDecos t ds sc s wrs ((w,r):xs) = do
 createDecos _ _ _ _ _ [] = return []
 
 createDecoWindow :: Theme -> Rectangle -> X Window
-createDecoWindow t r = let mask = Just (exposureMask .|. buttonPressMask) in
-                       createNewWindow r mask (inactiveColor t) True
+createDecoWindow t r = do
+  let mask = Just (exposureMask .|. buttonPressMask)
+  w <- createNewWindow r mask (inactiveColor t) True
+  d <- asks display
+  io $ setClassHint d w (ClassHint "xmonad-decoration" "xmonad")
+  pure w
 
 showDecos :: [DecoWin] -> X ()
 showDecos = showWindows . catMaybes . map fst . filter (isJust . snd)
diff --git a/XMonad/Prompt.hs b/XMonad/Prompt.hs
index fa0efdd4..33982aa2 100644
--- a/XMonad/Prompt.hs
+++ b/XMonad/Prompt.hs
@@ -558,7 +558,7 @@ mkXPromptImplementation historyKey conf om = do
   fs <- initXMF (font conf)
   st' <- io $
     bracket
-      (createWin d rw conf s)
+      (createPromptWin d rw conf s)
       (destroyWindow d)
       (\w ->
         bracket
@@ -1395,8 +1395,8 @@ redrawWindows c = do
     l  -> redrawComplWin l
   io $ sync d False
 
-createWin :: Display -> Window -> XPConfig -> Rectangle -> IO Window
-createWin d rw c s = do
+createPromptWin :: Display -> Window -> XPConfig -> Rectangle -> IO Window
+createPromptWin d rw c s = do
   let (x,y) = case position c of
                 Top -> (0,0)
                 Bottom -> (0, rect_height s - height c)
@@ -1406,6 +1406,7 @@ createWin d rw c s = do
                 _              -> rect_width s
   w <- mkUnmanagedWindow d (defaultScreenOfDisplay d) rw
                       (rect_x s + x) (rect_y s + fi y) width (height c)
+  setClassHint d w (ClassHint "xmonad-prompt" "xmonad")
   mapWindow d w
   return w