diff --git a/Lib/idlelib/Bindings.py b/Lib/idlelib/Bindings.py
index 13e2a3346fe..74a93d3b141 100644
--- a/Lib/idlelib/Bindings.py
+++ b/Lib/idlelib/Bindings.py
@@ -10,6 +10,7 @@ windows.
 """
 import sys
 from idlelib.configHandler import idleConf
+from idlelib import macosxSupport
 
 menudefs = [
  # underscore prefixes character to underscore
@@ -80,7 +81,7 @@ menudefs = [
    ]),
 ]
 
-if sys.platform == 'darwin' and '.app' in sys.executable:
+if macosxSupport.runningAsOSXApp():
     # Running as a proper MacOS application bundle. This block restructures
     # the menus a little to make them conform better to the HIG.
 
diff --git a/Lib/idlelib/EditorWindow.py b/Lib/idlelib/EditorWindow.py
index 1512c464af4..38ae7b60aa4 100644
--- a/Lib/idlelib/EditorWindow.py
+++ b/Lib/idlelib/EditorWindow.py
@@ -363,7 +363,7 @@ class EditorWindow(object):
             underline, label = prepstr(label)
             menudict[name] = menu = Menu(mbar, name=name)
             mbar.add_cascade(label=label, menu=menu, underline=underline)
-        if sys.platform == 'darwin' and '.framework' in sys.executable:
+        if macosxSupport.runningAsOSXApp():
             # Insert the application menu
             menudict['application'] = menu = Menu(mbar, name='apple')
             mbar.add_cascade(label='IDLE', menu=menu)
diff --git a/Lib/idlelib/MultiCall.py b/Lib/idlelib/MultiCall.py
index 1c40638402a..47f402d3261 100644
--- a/Lib/idlelib/MultiCall.py
+++ b/Lib/idlelib/MultiCall.py
@@ -32,6 +32,7 @@ Each function will be called at most once for each event.
 import sys
 import re
 import tkinter
+from idlelib import macosxSupport
 
 # the event type constants, which define the meaning of mc_type
 MC_KEYPRESS=0; MC_KEYRELEASE=1; MC_BUTTONPRESS=2; MC_BUTTONRELEASE=3;
@@ -44,7 +45,7 @@ MC_SHIFT = 1<<0; MC_CONTROL = 1<<2; MC_ALT = 1<<3; MC_META = 1<<5
 MC_OPTION = 1<<6; MC_COMMAND = 1<<7
 
 # define the list of modifiers, to be used in complex event types.
-if sys.platform == "darwin" and sys.executable.count(".app"):
+if macosxSupport.runningAsOSXApp():
     _modifiers = (("Shift",), ("Control",), ("Option",), ("Command",))
     _modifier_masks = (MC_SHIFT, MC_CONTROL, MC_OPTION, MC_COMMAND)
 else:
diff --git a/Lib/idlelib/keybindingDialog.py b/Lib/idlelib/keybindingDialog.py
index f5d32efa636..b99c5e0d8c0 100644
--- a/Lib/idlelib/keybindingDialog.py
+++ b/Lib/idlelib/keybindingDialog.py
@@ -4,6 +4,7 @@ Dialog for building Tkinter accelerator key bindings
 from tkinter import *
 import tkinter.messagebox as tkMessageBox
 import string
+from idlelib import macosxSupport
 
 class GetKeysDialog(Toplevel):
     def __init__(self,parent,title,action,currentKeySequences):
@@ -133,7 +134,7 @@ class GetKeysDialog(Toplevel):
         config-keys.def must use the same ordering.
         """
         import sys
-        if sys.platform == 'darwin' and sys.argv[0].count('.app'):
+        if macosxSupport.runningAsOSXApp():
             self.modifiers = ['Shift', 'Control', 'Option', 'Command']
         else:
             self.modifiers = ['Control', 'Alt', 'Shift']
diff --git a/Lib/idlelib/macosxSupport.py b/Lib/idlelib/macosxSupport.py
index 9f92b6c9dab..e759157444a 100644
--- a/Lib/idlelib/macosxSupport.py
+++ b/Lib/idlelib/macosxSupport.py
@@ -6,8 +6,12 @@ import sys
 import tkinter
 
 def runningAsOSXApp():
-    """ Returns True iff running from the IDLE.app bundle on OSX """
-    return (sys.platform == 'darwin' and 'IDLE.app' in sys.argv[0])
+    """
+    Returns True if Python is running from within an app on OSX.
+    If so, assume that Python was built with Aqua Tcl/Tk rather than
+    X11 Tck/Tk.
+    """
+    return (sys.platform == 'darwin' and '.app' in sys.executable)
 
 def addOpenEventSupport(root, flist):
     """
diff --git a/Mac/IDLE/IDLE.app/Contents/MacOS/IDLE b/Mac/IDLE/IDLE.app/Contents/MacOS/IDLE
index ecf29bf0875..61b02fff6bd 100755
--- a/Mac/IDLE/IDLE.app/Contents/MacOS/IDLE
+++ b/Mac/IDLE/IDLE.app/Contents/MacOS/IDLE
@@ -1,4 +1,4 @@
-#!%prefix%/Resources/Python.app/Contents/MacOS/Python3
+#!%prefix%/Resources/Python.app/Contents/MacOS/%exe%
 
 import sys, os
 execdir = os.path.dirname(sys.argv[0])
diff --git a/Mac/IDLE/IDLE.app/Contents/Resources/idlemain.py b/Mac/IDLE/IDLE.app/Contents/Resources/idlemain.py
index 9b5273899f6..d6803ba832c 100644
--- a/Mac/IDLE/IDLE.app/Contents/Resources/idlemain.py
+++ b/Mac/IDLE/IDLE.app/Contents/Resources/idlemain.py
@@ -3,8 +3,6 @@ Bootstrap script for IDLE as an application bundle.
 """
 import sys, os
 
-from idlelib.PyShell import main
-
 # Change the current directory the user's home directory, that way we'll get
 # a more useful default location in the open/save dialogs.
 os.chdir(os.path.expanduser('~/Documents'))
@@ -13,10 +11,54 @@ os.chdir(os.path.expanduser('~/Documents'))
 # Make sure sys.executable points to the python interpreter inside the
 # framework, instead of at the helper executable inside the application
 # bundle (the latter works, but doesn't allow access to the window server)
-if sys.executable.endswith('-32'):
-    sys.executable = os.path.join(sys.prefix, 'bin', 'python-32')
-else:
-    sys.executable = os.path.join(sys.prefix, 'bin', 'python')
+#
+#  .../IDLE.app/
+#       Contents/
+#           MacOS/
+#               IDLE (a python script)
+#               Python{-32} (symlink)
+#           Resources/
+#               idlemain.py (this module)
+#               ...
+#
+# ../IDLE.app/Contents/MacOS/Python{-32} is symlinked to
+#       ..Library/Frameworks/Python.framework/Versions/m.n
+#                   /Resources/Python.app/Contents/MacOS/Python{-32}
+#       which is the Python interpreter executable
+#
+# The flow of control is as follows:
+# 1. IDLE.app is launched which starts python running the IDLE script
+# 2. IDLE script exports
+#       PYTHONEXECUTABLE = .../IDLE.app/Contents/MacOS/Python{-32}
+#           (the symlink to the framework python)
+# 3. IDLE script alters sys.argv and uses os.execve to replace itself with
+#       idlemain.py running under the symlinked python.
+#       This is the magic step.
+# 4. During interpreter initialization, because PYTHONEXECUTABLE is defined,
+#    sys.executable may get set to an unuseful value.
+#
+# (Note that the IDLE script and the setting of PYTHONEXECUTABLE is
+#  generated automatically by bundlebuilder in the Python 2.x build.
+#  Also, IDLE invoked via command line, i.e. bin/idle, bypasses all of
+#  this.)
+#
+# Now fix up the execution environment before importing idlelib.
+
+# Reset sys.executable to its normal value, the actual path of
+# the interpreter in the framework, by following the symlink
+# exported in PYTHONEXECUTABLE.
+pyex = os.environ['PYTHONEXECUTABLE']
+sys.executable = os.path.join(os.path.dirname(pyex), os.readlink(pyex))
+
+# Remove any sys.path entries for the Resources dir in the IDLE.app bundle.
+p = pyex.partition('.app')
+if p[2].startswith('/Contents/MacOS/Python'):
+    sys.path = [value for value in sys.path if
+            value.partition('.app') != (p[0], p[1], '/Contents/Resources')]
+
+# Unexport PYTHONEXECUTABLE so that the other Python processes started
+# by IDLE have a normal sys.executable.
+del os.environ['PYTHONEXECUTABLE']
 
 # Look for the -psn argument that the launcher adds and remove it, it will
 # only confuse the IDLE startup code.
@@ -25,6 +67,7 @@ for idx, value in enumerate(sys.argv):
         del sys.argv[idx]
         break
 
-#argvemulator.ArgvCollector().mainloop()
+# Now it is safe to import idlelib.
+from idlelib.PyShell import main
 if __name__ == '__main__':
     main()
diff --git a/Mac/Makefile.in b/Mac/Makefile.in
index f28d1ea1936..e847ba90882 100644
--- a/Mac/Makefile.in
+++ b/Mac/Makefile.in
@@ -215,7 +215,7 @@ install_Python4way: install_Python
 
 install_IDLE:
 	test -d "$(DESTDIR)$(PYTHONAPPSDIR)" || mkdir -p "$(DESTDIR)$(PYTHONAPPSDIR)"
-	-test -d "$(DESTDIR)$(PYTHONAPPSDIR)/IDLE.app" && rm -r "$(DESTDIR)$(PYTHONAPPSDIR)/IDLE.app"
+	-test -d "$(DESTDIR)$(PYTHONAPPSDIR)/IDLE.app" && rm -rf "$(DESTDIR)$(PYTHONAPPSDIR)/IDLE.app"
 	/bin/cp -PR "$(srcdir)/IDLE/IDLE.app" "$(DESTDIR)$(PYTHONAPPSDIR)"
 	ln -sf $(INSTALLED_PYTHONAPP) "$(DESTDIR)$(PYTHONAPPSDIR)/IDLE.app/Contents/MacOS/Python"
 	sed -e "s!%prefix%!$(prefix)!g" -e 's!%exe%!$(PYTHONFRAMEWORK)!g' < "$(srcdir)/IDLE/IDLE.app/Contents/MacOS/IDLE" > "$(DESTDIR)$(PYTHONAPPSDIR)/IDLE.app/Contents/MacOS/IDLE"