diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,13 @@
+# Change Log / Release Notes
+
+## 1.0.1 (March 20, 2021)
+
+### Bug Fixes
+
+- Fix failing on killing previous application instance
+
+  https://github.com/unclechu/place-cursor-at/issues/4
+
+## 1.0.0 (March 20, 2021)
+
+- First stable release
diff --git a/place-cursor-at.cabal b/place-cursor-at.cabal
--- a/place-cursor-at.cabal
+++ b/place-cursor-at.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 66d39f7b6b91273a09289c622d5c81b8bb6f010ee69d032997ed77412a1f96f5
+-- hash: 28a469787c7689160b683cbbdb65c1e82d866a1631cfe3a311b51a2ff5c70c49
 
 name:           place-cursor-at
-version:        1.0.0
+version:        1.0.1
 synopsis:       A utility for X11 that moves the mouse cursor using the keyboard
 category:       Utility, GUI, Desktop, Desktop Environment, X11
 homepage:       https://github.com/unclechu/place-cursor-at#readme
@@ -17,10 +17,11 @@
 copyright:      Copyright © 2017–2021 Viacheslav Lotsmanov
 license:        GPL-3
 license-file:   LICENSE
-tested-with:    GHC ==8.10.4 || ==8.8.4 || ==8.6.4
+tested-with:    GHC == 8.10.4 || == 8.8.4 || == 8.6.4
 build-type:     Simple
 extra-source-files:
     README.md
+    CHANGELOG.md
 
 source-repository head
   type: git
diff --git a/src/place-cursor-at.hs b/src/place-cursor-at.hs
--- a/src/place-cursor-at.hs
+++ b/src/place-cursor-at.hs
@@ -13,8 +13,8 @@
 
 import Data.Bifunctor (first)
 import Data.Bits ((.|.))
-import Data.Bool (bool)
 import Data.Char (toUpper)
+import Data.Function (fix)
 import Data.Functor ((<&>))
 import Data.List (find)
 import Numeric.Natural
@@ -241,38 +241,23 @@
          waitBeforeItIsDone doneHandler >>= either throwIO pure
 
 
--- | Kill previous instance of *place-cursor-at*.
---
--- FIXME In some cases it fails the killer with this exception in the log:
---
--- @
--- X Error of failed request:  BadValue (integer parameter out of range for operation)
---   Major opcode of failed request:  113 (X_KillClient)
---   Value in failed request:  0x6000002
---   Serial number of failed request:  259
---   Current serial number in output stream:  260
--- @
---
--- I have no idea what the heck is this. I tried many ways to fix this with no success.
+-- | Kill previous instance of *place-cursor-at*
 killPreviousInstanceIfExists ∷ Display → IO ()
 killPreviousInstanceIfExists dpy = go where
-  go = traverseChildWindows (defaultRootWindow dpy)
-  kill = killClient dpy
-
-  traverseChildWindows ∷ Window → IO ()
-  traverseChildWindows wnd = killEmRecursively where
-    killEmRecursively =
-      getAllWindowsList wnd
-      >>= foldM reducer mempty
-      >>= (mapM_ kill *** mapM_ traverseChildWindows) • uncurry (>>)
+  go = findPreyToKill (defaultRootWindow dpy) >>= mapM_ (killClient dpy)
 
-    reducer ∷ acc ~ ([Window], [Window]) ⇒ acc → Window → IO acc
-    reducer acc x = f where
-      f = isPlaceCursorAtWindow x <&> \is → (x `appendIf` is *** x `appendIf` not is) acc
-      appendIf wndToAppend = bool id (⧺ [wndToAppend])
+  findPreyToKill ∷ Window → IO [Window]
+  findPreyToKill =
+    ($ []) $ fix $ \again acc !wnd →
+      isPlaceCursorAtWindow wnd >>= \case
+        False → foldM again acc =<< getChildWindows wnd
+        True → slurpAllChildren acc wnd
+    where
+      slurpAllChildren acc !wnd =
+        foldM slurpAllChildren (wnd : acc) =<< getChildWindows wnd
 
-  getAllWindowsList ∷ Window → IO [Window]
-  getAllWindowsList wnd = queryTree dpy wnd <&> \(_, _, x) → x
+  getChildWindows ∷ Window → IO [Window]
+  getChildWindows wnd = queryTree dpy wnd <&> \(_, _, x) → x
 
   isPlaceCursorAtWindow ∷ Window → IO Bool
   isPlaceCursorAtWindow wnd = x where