diff --git a/cibuildwheel/macos.py b/cibuildwheel/macos.py
index d98b9731..20cad75b 100644
--- a/cibuildwheel/macos.py
+++ b/cibuildwheel/macos.py
@@ -19,10 +19,14 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
         PythonConfiguration(version='3.6', identifier='cp36-macosx_10_6_intel', url='https://www.python.org/ftp/python/3.6.0/python-3.6.0-macosx10.6.pkg'),
     ]
 
-    def shell(args, env=None, cwd=None):
+    def call(args, env=None, cwd=None, shell=False):
         # print the command executing for the logs
-        print('+ ' + ' '.join(shlex_quote(a) for a in args))
-        return subprocess.check_call(args, env=env, cwd=cwd)
+        if shell:
+            print('+ %s' % args)
+        else:
+            print('+ ' + ' '.join(shlex_quote(a) for a in args))
+
+        return subprocess.check_call(args, env=env, cwd=cwd, shell=shell)
 
     for config in python_configurations:
         if skip(config.identifier):
@@ -30,9 +34,9 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             continue
 
         # download the pkg
-        shell(['curl', '-L', '-o', '/tmp/Python.pkg', config.url])
+        call(['curl', '-L', '-o', '/tmp/Python.pkg', config.url])
         # install
-        shell(['sudo', 'installer', '-pkg', '/tmp/Python.pkg', '-target', '/'])
+        call(['sudo', 'installer', '-pkg', '/tmp/Python.pkg', '-target', '/'])
 
         env = os.environ.copy()
         env['PATH'] = os.pathsep.join([
@@ -44,14 +48,14 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
         pip = 'pip3' if config.version[0] == '3' else 'pip2'
 
         # check what version we're on
-        shell(['which', python], env=env)
-        shell([python, '--version'], env=env)
+        call(['which', python], env=env)
+        call([python, '--version'], env=env)
 
         # install pip & wheel
-        shell([python, '-m', 'ensurepip', '--upgrade'], env=env)
-        shell([pip, '--version'], env=env)
-        shell([pip, 'install', 'wheel'], env=env)
-        shell([pip, 'install', 'delocate'], env=env)
+        call([python, '-m', 'ensurepip', '--upgrade'], env=env)
+        call([pip, '--version'], env=env)
+        call([pip, 'install', 'wheel'], env=env)
+        call([pip, 'install', 'delocate'], env=env)
 
         # setup dirs
         if os.path.exists('/tmp/built_wheel'):
@@ -64,10 +68,10 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
         # run the before_build command
         if before_build:
             before_build_prepared = prepare_command(before_build, python=python, pip=pip)
-            shell(shlex.split(before_build_prepared), env=env)
+            call(before_build_prepared, env=env, shell=True)
 
         # build the wheel
-        shell([pip, 'wheel', project_dir, '-w', '/tmp/built_wheel', '--no-deps'], env=env)
+        call([pip, 'wheel', project_dir, '-w', '/tmp/built_wheel', '--no-deps'], env=env)
         built_wheel = glob('/tmp/built_wheel/*.whl')[0]
 
         if built_wheel.endswith('none-any.whl'):
@@ -75,24 +79,24 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
             shutil.move(built_wheel, '/tmp/delocated_wheel')
         else:
             # list the dependencies
-            shell(['delocate-listdeps', built_wheel], env=env)
+            call(['delocate-listdeps', built_wheel], env=env)
             # rebuild the wheel with shared libraries included and place in output dir
-            shell(['delocate-wheel', '-w', '/tmp/delocated_wheel', built_wheel], env=env)
+            call(['delocate-wheel', '-w', '/tmp/delocated_wheel', built_wheel], env=env)
         delocated_wheel = glob('/tmp/delocated_wheel/*.whl')[0]
 
         # install the wheel
-        shell([pip, 'install', delocated_wheel], env=env)
+        call([pip, 'install', delocated_wheel], env=env)
 
         # test the wheel
         if test_requires:
-            shell([pip, 'install'] + test_requires, env=env)
+            call([pip, 'install'] + test_requires, env=env)
         if test_command:
             # run the tests from $HOME, with an absolute path in the command
             # (this ensures that Python runs the tests against the installed wheel
             # and not the repo code)
             abs_project_dir = os.path.abspath(project_dir)
             test_command_absolute = test_command.format(project=abs_project_dir)
-            shell(shlex.split(test_command_absolute), cwd=os.environ['HOME'], env=env)
+            call(shlex.split(test_command_absolute), cwd=os.environ['HOME'], env=env)
 
         # we're all done here; move it to output
         shutil.move(delocated_wheel, output_dir)