Quote the paths in the event that they contain spaces.
diff --git a/Lib/idlelib/idle.bat b/Lib/idlelib/idle.bat
index 4e67868..cc653dc 100755
--- a/Lib/idlelib/idle.bat
+++ b/Lib/idlelib/idle.bat
@@ -1,4 +1,4 @@
 @echo off
 rem Start IDLE using the appropriate Python interpreter
 set CURRDIR=%~dp0
-start %CURRDIR%..\..\pythonw.exe %CURRDIR%idle.pyw %1 %2 %3 %4 %5 %6 %7 %8 %9
+start "%CURRDIR%..\..\pythonw.exe" "%CURRDIR%idle.pyw" %1 %2 %3 %4 %5 %6 %7 %8 %9