diff --git a/Mac/Tools/IDE/PythonIDEMain.py b/Mac/Tools/IDE/PythonIDEMain.py
index 51072e1..1b2b3b7 100644
--- a/Mac/Tools/IDE/PythonIDEMain.py
+++ b/Mac/Tools/IDE/PythonIDEMain.py
@@ -46,7 +46,7 @@
 		# With -D option (OSX command line only) keep stderr, for debugging the IDE
 		# itself.
 		debug_stderr = None
-		if sys.argv[1] == '-D':
+		if len(sys.argv) >= 2 and sys.argv[1] == '-D':
 			debug_stderr = sys.stderr
 			del sys.argv[1]
 		PyConsole.installoutput()