diff --git a/tests/test_clipboard.py b/tests/test_clipboard.py
index 96aec4e..1b8c5eb 100644
--- a/tests/test_clipboard.py
+++ b/tests/test_clipboard.py
@@ -16,14 +16,14 @@ except ImportError:
 def test_copy():
 
     with mock.patch('subprocess.Popen') as Popen, \
-            mock.patch('subprocess.call') as call:
+            mock.patch('subprocess.call', return_value=0) as call:
 
         # Mock out the subprocess calls
         p = mock.Mock()
         p.communicate = mock.Mock()
+        
         Popen.return_value = p
 
-        call.return_value = 0
         copy('test', 'xsel -b -i')
         assert Popen.call_args[0][0] == ['xsel', '-b', '-i']
         p.communicate.assert_called_with(input='test'.encode('utf-8'))
@@ -32,4 +32,16 @@ def test_copy():
         assert Popen.call_args[0][0] == ['xclip']
         p.communicate.assert_called_with(input='test ❤'.encode('utf-8'))
 
-    # Need OSX tests, can't simulate sys.platform
+    with mock.patch('subprocess.Popen') as Popen, \
+            mock.patch('subprocess.call', return_value=0) as call:
+
+        # Simulate OSX
+        mock.patch('sys.platform', return_value='darwin')
+        
+        p = mock.Mock()
+        p.communicate = mock.Mock()
+        Popen.return_value = p
+
+        copy('test', 'pbcopy w')
+        assert Popen.call_args[0][0] == ['pbcopy', 'w']
+        p.communicate.assert_called_with(input='test'.encode('utf-8'))