--- a/build/upload.py
+++ b/build/upload.py
@@ -52,17 +52,18 @@
 #
 # All files to be uploaded should be passed as commandline arguments to this
 # script. The script takes one other parameter, --base-path, which you can use
 # to indicate that files should be uploaded including their paths relative
 # to the base path.
 
 import sys, os
 from optparse import OptionParser
-from subprocess import PIPE, Popen, check_call
+from subprocess import Popen, PIPE
+from util import check_call
 
 def RequireEnvironmentVariable(v):
     """Return the value of the environment variable named v, or print
     an error and exit if it's unset (or empty)."""
     if not v in os.environ or os.environ[v] == "":
         print "Error: required environment variable %s not set" % v
         sys.exit(1)
     return os.environ[v]

new file mode 100644
--- /dev/null
+++ b/build/util.py
@@ -0,0 +1,50 @@
+#!/usr/bin/python
+#
+# ***** BEGIN LICENSE BLOCK *****
+# Version: MPL 1.1/GPL 2.0/LGPL 2.1
+#
+# The contents of this file are subject to the Mozilla Public License Version
+# 1.1 (the "License"); you may not use this file except in compliance with
+# the License. You may obtain a copy of the License at
+# http://www.mozilla.org/MPL/
+#
+# Software distributed under the License is distributed on an "AS IS" basis,
+# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+# for the specific language governing rights and limitations under the
+# License.
+#
+# The Original Code is mozilla.org code.
+#
+# The Initial Developer of the Original Code is
+# The Mozilla Foundation 
+# Portions created by the Initial Developer are Copyright (C) 2008
+# the Initial Developer. All Rights Reserved.
+#
+# Contributor(s):
+#  Ted Mielczarek <ted.mielczarek@gmail.com>
+#
+# Alternatively, the contents of this file may be used under the terms of
+# either the GNU General Public License Version 2 or later (the "GPL"), or
+# the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+# in which case the provisions of the GPL or the LGPL are applicable instead
+# of those above. If you wish to allow use of your version of this file only
+# under the terms of either the GPL or the LGPL, and not to allow others to
+# use your version of this file under the terms of the MPL, indicate your
+# decision by deleting the provisions above and replace them with the notice
+# and other provisions required by the GPL or the LGPL. If you do not delete
+# the provisions above, a recipient may use your version of this file under
+# the terms of any one of the MPL, the GPL or the LGPL.
+#
+# ***** END LICENSE BLOCK *****
+
+try:
+    from subprocess import check_call
+except ImportError:
+    import subprocess
+    def check_call(*popenargs, **kwargs):
+        retcode = subprocess.call(*popenargs, **kwargs)
+        if retcode:
+            cmd = kwargs.get("args")
+            if cmd is None:
+                cmd = popenargs[0]
+                raise Exception("Command '%s' returned non-zero exit status %i" % (cmd, retcode))

--- a/client.py
+++ b/client.py
@@ -10,17 +10,17 @@ LIBFFI_DIRS = (('js/ctypes/libffi', 'lib
 CVSROOT_MOZILLA = ':pserver:anonymous@cvs-mirror.mozilla.org:/cvsroot'
 CVSROOT_LIBFFI = ':pserver:anoncvs@sources.redhat.com:/cvs/libffi'
 
 import os
 import sys
 import datetime
 import shutil
 from optparse import OptionParser
-from subprocess import check_call
+from build.util import check_call
 
 topsrcdir = os.path.dirname(__file__)
 if topsrcdir == '':
     topsrcdir = '.'
 
 def check_call_noisy(cmd, *args, **kwargs):
     print "Executing command:", cmd
     check_call(cmd, *args, **kwargs)