diff -r 82607e7c24c7 Lib/test/test_bz2.py
--- a/Lib/test/test_bz2.py	Fri Nov 11 12:07:48 2016 +0200
+++ b/Lib/test/test_bz2.py	Fri Nov 11 12:38:25 2016 +0200
@@ -8,6 +8,7 @@ import pickle
 import glob
 import pathlib
 import random
+import shutil
 import subprocess
 import sys
 from test.support import unlink
@@ -22,6 +23,7 @@ except ImportError:
 bz2 = support.import_module('bz2')
 from bz2 import BZ2File, BZ2Compressor, BZ2Decompressor
 
+has_cmdline_bunzip2 = None
 
 class BaseTest(unittest.TestCase):
     "Base for other testcases."
@@ -74,23 +76,15 @@ class BaseTest(unittest.TestCase):
         if os.path.isfile(self.filename):
             os.unlink(self.filename)
 
-    if sys.platform == "win32":
-        # bunzip2 isn't available to run on Windows.
-        def decompress(self, data):
+    @staticmethod
+    def decompress(data):
+        global has_cmdline_bunzip2
+        if has_cmdline_bunzip2 is None:
+            has_cmdline_bunzip2 = bool(shutil.which('bunzip2'))
+        if has_cmdline_bunzip2:
+            return subprocess.check_output(['bunzip2'], input=data)
+        else:
             return bz2.decompress(data)
-    else:
-        def decompress(self, data):
-            pop = subprocess.Popen("bunzip2", shell=True,
-                                   stdin=subprocess.PIPE,
-                                   stdout=subprocess.PIPE,
-                                   stderr=subprocess.STDOUT)
-            pop.stdin.write(data)
-            pop.stdin.close()
-            ret = pop.stdout.read()
-            pop.stdout.close()
-            if pop.wait() != 0:
-                ret = bz2.decompress(data)
-            return ret
 
 
 class BZ2FileTest(BaseTest):