diff --git a/Lib/idlelib/Icons/idle.ico b/Lib/idlelib/Icons/idle.ico
new file mode 100644
index 00000000000..3357aef1488
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diff --git a/Lib/idlelib/Icons/idle_16.gif b/Lib/idlelib/Icons/idle_16.gif
new file mode 100644
index 00000000000..9f001b1d79c
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diff --git a/Lib/idlelib/Icons/idle_16.png b/Lib/idlelib/Icons/idle_16.png
new file mode 100644
index 00000000000..6abde0af90c
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diff --git a/Lib/idlelib/Icons/idle_32.gif b/Lib/idlelib/Icons/idle_32.gif
new file mode 100644
index 00000000000..af5b2d52cce
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diff --git a/Lib/idlelib/Icons/idle_32.png b/Lib/idlelib/Icons/idle_32.png
new file mode 100644
index 00000000000..41b70dbc377
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diff --git a/Lib/idlelib/Icons/idle_48.gif b/Lib/idlelib/Icons/idle_48.gif
new file mode 100644
index 00000000000..fc5304f31ee
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diff --git a/Lib/idlelib/Icons/idle_48.png b/Lib/idlelib/Icons/idle_48.png
new file mode 100644
index 00000000000..e5fa9280e21
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diff --git a/Lib/idlelib/PyShell.py b/Lib/idlelib/PyShell.py
index 55fd3574d4f..2e5ebb233b8 100755
--- a/Lib/idlelib/PyShell.py
+++ b/Lib/idlelib/PyShell.py
@@ -16,7 +16,7 @@
 
 import linecache
 from code import InteractiveInterpreter
-from platform import python_version
+from platform import python_version, system
 
 try:
     from tkinter import *
@@ -1524,6 +1524,18 @@ def main():
     # start editor and/or shell windows:
     root = Tk(className="Idle")
 
+    # set application icon
+    icondir = os.path.join(os.path.dirname(__file__), 'Icons')
+    if system() == 'Windows':
+        iconfile = os.path.join(icondir, 'idle.ico')
+        root.wm_iconbitmap(default=iconfile)
+    elif TkVersion >= 8.5:
+        ext = '.png' if TkVersion >= 8.6 else '.gif'
+        iconfiles = [os.path.join(icondir, 'idle_%d%s' % (size, ext))
+                     for size in (16, 32, 48)]
+        icons = [PhotoImage(file=iconfile) for iconfile in iconfiles]
+        root.wm_iconphoto(True, *icons)
+
     fixwordbreaks(root)
     root.withdraw()
     flist = PyShellFileList(root)
diff --git a/Misc/NEWS b/Misc/NEWS
index f3f94bfb836..ae5f83a1537 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -316,6 +316,9 @@ Library
 IDLE
 ----
 
+- Issue #20406: Use Python application icons for Idle window title bars.
+  Patch mostly by Serhiy Storchaka.
+
 - Update the python.gif icon for the Idle classbrowser and pathbowser
   from the old green snake to the new new blue and yellow snakes.