diff -ur ./Lib/os.py /Lib/os.py
--- ./Lib/os.py	2009-09-26 13:48:46.000000000 -0700
+++ /Lib/os.py	2012-02-21 14:47:26.000000000 -0700
@@ -58,6 +58,10 @@
         ['Windows'],
         [['cmd.exe', '/c'], ['command.com', '/c']]
         ],
+               ibmi=[
+        ['OS/400'],
+        [['/QOpenSys/usr/bin/sh', '-c']]
+        ],
                posix=[
         [], # posix is a fallback, instead of matching names
         [['/bin/sh', '-c']]
diff -ur ./Lib/subprocess.py /Lib/subprocess.py
--- ./Lib/subprocess.py	2012-02-21 13:06:16.000000000 -0700
+++ /Lib/subprocess.py	2012-02-21 14:47:08.000000000 -0700
@@ -1243,8 +1243,10 @@
                 args[0] = executable
 
             builder = java.lang.ProcessBuilder(args)
-            # os.environ may be inherited for compatibility with CPython
-            self._setup_env(dict(os.environ if env is None else env),
+            ostype = os.get_os_type ()
+            if ostype != 'ibmi' or env is not None:
+                # os.environ may be inherited for compatibility with CPython
+                self._setup_env(dict(os.environ if env is None else env),
                             builder.environment())
 
             if cwd is None: