diff --git a/python/mozboot/bin/bootstrap.py b/python/mozboot/bin/bootstrap.py
index cd5cf8920e46..0e2c3e1c286e 100755
--- a/python/mozboot/bin/bootstrap.py
+++ b/python/mozboot/bin/bootstrap.py
@@ -10,7 +10,9 @@
 # bootstrap support. It does this through various means, including fetching
 # content from the upstream source repository.
 
-from __future__ import print_function, unicode_literals
+# If we add unicode_literals, optparse breaks on Python 2.6.1 (which is needed
+# to support OS X 10.6).
+from __future__ import print_function
 
 import os
 import shutil
diff --git a/python/mozboot/mozboot/base.py b/python/mozboot/mozboot/base.py
index 96de676ba18a..66b998f920f1 100644
--- a/python/mozboot/mozboot/base.py
+++ b/python/mozboot/mozboot/base.py
@@ -52,3 +52,23 @@ class BaseBootstrapper(object):
         command.extend(packages)
 
         self.run_as_root(command)
+
+    def check_output(self, *args, **kwargs):
+        """Run subprocess.check_output even if Python doesn't provide it."""
+        fn = getattr(subprocess, 'check_output', BaseBootstrapper._check_output)
+
+        return fn(*args, **kwargs)
+
+    @staticmethod
+    def _check_output(*args, **kwargs):
+        """Python 2.6 compatible implementation of subprocess.check_output."""
+        proc = subprocess.Popen(stdout=subprocess.PIPE, *args, **kwargs)
+        output, unused_err = proc.communicate()
+        retcode = proc.poll()
+        if retcode:
+            cmd = kwargs.get('args', args[0])
+            e = subprocess.CalledProcessError(retcode, cmd)
+            e.output = output
+            raise e
+
+        return output
diff --git a/python/mozboot/mozboot/bootstrap.py b/python/mozboot/mozboot/bootstrap.py
index 1a8fb623109a..9b4b9567d068 100644
--- a/python/mozboot/mozboot/bootstrap.py
+++ b/python/mozboot/mozboot/bootstrap.py
@@ -2,7 +2,8 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this file,
 # You can obtain one at http://mozilla.org/MPL/2.0/.
 
-from __future__ import print_function, unicode_literals
+# If we add unicode_literals, Python 2.6.1 (required for OS X 10.6) breaks.
+from __future__ import print_function
 
 import platform
 import sys
diff --git a/python/mozboot/mozboot/osx.py b/python/mozboot/mozboot/osx.py
index e17347a2df66..483d8b8ada4d 100644
--- a/python/mozboot/mozboot/osx.py
+++ b/python/mozboot/mozboot/osx.py
@@ -119,7 +119,7 @@ class OSXBootstrapper(BaseBootstrapper):
         # Once Xcode is installed, you need to agree to the license before you can
         # use it.
         try:
-            output = subprocess.check_output(['/usr/bin/xcrun', 'clang'],
+            output = self.check_output(['/usr/bin/xcrun', 'clang'],
                 stderr=subprocess.STDOUT)
         except subprocess.CalledProcessError as e:
              if 'license' in e.output:
@@ -135,7 +135,7 @@ class OSXBootstrapper(BaseBootstrapper):
                 print(INSTALL_XCODE_COMMAND_LINE_TOOLS_STEPS)
                 sys.exit(1)
 
-            output = subprocess.check_output(['/usr/bin/clang', '--version'])
+            output = self.check_output(['/usr/bin/clang', '--version'])
             match = RE_CLANG_VERSION.search(output)
             if match is None:
                 raise Exception('Could not determine Clang version.')
@@ -170,7 +170,7 @@ class OSXBootstrapper(BaseBootstrapper):
         brew = self.which('brew')
         assert brew is not None
 
-        installed = subprocess.check_output([brew, 'list']).split()
+        installed = self.check_output([brew, 'list']).split()
 
         if 'python' not in installed:
             self.ensure_xquartz()