diff --git a/cmake/CMakeLists_test.txt b/cmake/CMakeLists_test.txt
index bd3f379c..02de488e 100644
--- a/cmake/CMakeLists_test.txt
+++ b/cmake/CMakeLists_test.txt
@@ -29,6 +29,12 @@ if(WIN32)
 	)
 endif()
 
+if(APPLE)
+	list(APPEND integtests
+		${root_dir}/src/integtest/platform/COSXClipboardTests.cpp
+	)
+endif()
+
 set(inc
 	${root_dir}
 	${root_dir}/lib
diff --git a/lib/platform/COSXClipboard.cpp b/lib/platform/COSXClipboard.cpp
index 9cc47b4d..da46eb76 100644
--- a/lib/platform/COSXClipboard.cpp
+++ b/lib/platform/COSXClipboard.cpp
@@ -102,7 +102,12 @@ COSXClipboard::add(EFormat format, const CString & data)
 			CString osXData = converter->fromIClipboard(data);
 			CFStringRef flavorType = converter->getOSXFormat();
 			CFDataRef dataRef = CFDataCreate(kCFAllocatorDefault, (UInt8 *)osXData.data(), osXData.size());
-
+			
+			// integ tests showed that if you call add(...) twice, then the
+			// second call will actually fail to set clipboard data. calling
+			// empty() seems to solve this problem.
+			empty();
+			
 			PasteboardPutItemFlavor(
 					m_pboard,
 					(PasteboardItemID) 0,
diff --git a/src/integtest/IntegTestMain.cpp b/src/integtest/IntegTestMain.cpp
index 74af0872..011594f3 100644
--- a/src/integtest/IntegTestMain.cpp
+++ b/src/integtest/IntegTestMain.cpp
@@ -17,7 +17,9 @@
 
 #include <iostream>
 #include <gtest/gtest.h>
+#if SYSAPI_WIN32
 #include "CArchMiscWindows.h"
+#endif
 #include "CArch.h"
 
 int
diff --git a/src/integtest/platform/COSXClipboardTests.cpp b/src/integtest/platform/COSXClipboardTests.cpp
new file mode 100644
index 00000000..f9e6a19a
--- /dev/null
+++ b/src/integtest/platform/COSXClipboardTests.cpp
@@ -0,0 +1,162 @@
+/*
+ * synergy -- mouse and keyboard sharing utility
+ * Copyright (C) 2011 Chris Schoeneman, Nick Bolton, Sorin Sbarnea
+ * 
+ * This package is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * found in the file COPYING that should have accompanied this file.
+ * 
+ * This package is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <iostream>
+#include <gtest/gtest.h>
+#include "COSXClipboard.h"
+
+TEST(COSXClipboardTests, empty_openCalled_returnsTrue)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	
+	bool actual = clipboard.empty();
+	
+	EXPECT_EQ(true, actual);
+}
+
+TEST(COSXClipboardTests, empty_singleFormat_hasReturnsFalse)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	clipboard.add(COSXClipboard::kText, "synergy rocks!");
+	
+	clipboard.empty();
+	
+	bool actual = clipboard.has(COSXClipboard::kText);
+	EXPECT_EQ(false, actual);
+}
+
+TEST(COSXClipboardTests, add_newValue_valueWasStored)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	
+	clipboard.add(IClipboard::kText, "synergy rocks!");
+	
+	CString actual = clipboard.get(IClipboard::kText);
+	EXPECT_EQ("synergy rocks!", actual);
+}
+
+TEST(COSXClipboardTests, add_replaceValue_valueWasReplaced)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	
+	clipboard.add(IClipboard::kText, "synergy rocks!");
+	clipboard.add(IClipboard::kText, "maxivista sucks"); // haha, just kidding.
+	
+	CString actual = clipboard.get(IClipboard::kText);
+	EXPECT_EQ("maxivista sucks", actual);
+}
+
+TEST(COSXClipboardTests, open_timeIsZero_returnsTrue)
+{
+	COSXClipboard clipboard;
+	
+	bool actual = clipboard.open(0);
+	
+	EXPECT_EQ(true, actual);
+}
+
+TEST(COSXClipboardTests, open_timeIsOne_returnsTrue)
+{
+	COSXClipboard clipboard;
+	
+	bool actual = clipboard.open(1);
+	
+	EXPECT_EQ(true, actual);
+}
+
+TEST(COSXClipboardTests, close_isOpen_noErrors)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	
+	clipboard.close();
+	
+	// can't assert anything
+}
+
+TEST(COSXClipboardTests, getTime_openWithNoEmpty_returnsOne)
+{
+	COSXClipboard clipboard;
+	clipboard.open(1);
+	
+	COSXClipboard::Time actual = clipboard.getTime();
+	
+	// this behavior is different to that of CClipboard which only
+	// returns the value passed into open(t) after empty() is called.
+	EXPECT_EQ((UInt32)1, actual);
+}
+
+TEST(COSXClipboardTests, getTime_openAndEmpty_returnsOne)
+{
+	COSXClipboard clipboard;
+	clipboard.open(1);
+	clipboard.empty();
+	
+	COSXClipboard::Time actual = clipboard.getTime();
+	
+	EXPECT_EQ((UInt32)1, actual);
+}
+
+TEST(COSXClipboardTests, has_withFormatAdded_returnsTrue)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	clipboard.empty();
+	clipboard.add(IClipboard::kText, "synergy rocks!");
+	
+	bool actual = clipboard.has(IClipboard::kText);
+	
+	EXPECT_EQ(true, actual);
+}
+
+TEST(COSXClipboardTests, has_withNoFormats_returnsFalse)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	clipboard.empty();
+	
+	bool actual = clipboard.has(IClipboard::kText);
+	
+	EXPECT_EQ(false, actual);
+}
+
+TEST(COSXClipboardTests, get_withNoFormats_returnsEmpty)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	clipboard.empty();
+	
+	CString actual = clipboard.get(IClipboard::kText);
+	
+	EXPECT_EQ("", actual);
+}
+
+TEST(COSXClipboardTests, get_withFormatAdded_returnsExpected)
+{
+	COSXClipboard clipboard;
+	clipboard.open(0);
+	clipboard.empty();
+	clipboard.add(IClipboard::kText, "synergy rocks!");
+	
+	CString actual = clipboard.get(IClipboard::kText);
+	
+	EXPECT_EQ("synergy rocks!", actual);
+}