diff --git a/waflib/Tools/waf_unit_test.py b/waflib/Tools/waf_unit_test.py
index fb5b2e6a..54786072 100644
--- a/waflib/Tools/waf_unit_test.py
+++ b/waflib/Tools/waf_unit_test.py
@@ -224,7 +224,7 @@ class utest(Task.Task):
 		self.ut_exec = getattr(self.generator, 'ut_exec', [self.inputs[0].abspath()])
 		ut_cmd = getattr(self.generator, 'ut_cmd', False)
 		if ut_cmd:
-			self.ut_exec = shlex.split(ut_cmd % ' '.join(self.ut_exec))
+			self.ut_exec = shlex.split(ut_cmd % Utils.shell_escape(self.ut_exec))
 
 		return self.exec_command(self.ut_exec)
 
diff --git a/waflib/Utils.py b/waflib/Utils.py
index fc64fa05..669490ca 100644
--- a/waflib/Utils.py
+++ b/waflib/Utils.py
@@ -11,7 +11,7 @@ through Python versions 2.5 to 3.X and across different platforms (win32, linux,
 
 from __future__ import with_statement
 
-import atexit, os, sys, errno, inspect, re, datetime, platform, base64, signal, functools, time
+import atexit, os, sys, errno, inspect, re, datetime, platform, base64, signal, functools, time, shlex
 
 try:
 	import cPickle
@@ -577,10 +577,13 @@ def quote_define_name(s):
 	fu = fu.upper()
 	return fu
 
-re_sh = re.compile('\\s|\'|"')
-"""
-Regexp used for shell_escape below
-"""
+# shlex.quote didn't exist until python 3.3. Prior to that it was a non-documented
+# function in pipes.
+try:
+	shell_quote = shlex.quote
+except AttributeError:
+	import pipes
+	shell_quote = pipes.quote
 
 def shell_escape(cmd):
 	"""
@@ -589,7 +592,7 @@ def shell_escape(cmd):
 	"""
 	if isinstance(cmd, str):
 		return cmd
-	return ' '.join(repr(x) if re_sh.search(x) else x for x in cmd)
+	return ' '.join(shell_quote(x) for x in cmd)
 
 def h_list(lst):
 	"""