Hello, I have tried to compile the code on OSX10.7 and Xcode 4.6.3. The problem is the __weak attributes. If I compile the test app using Xcode 5.1.1, and then.. drop it on OSX10.7, it crashes. Actually, the commit that broke the compatibility is this one: https://github.com/rsms/chromium-tabs/commit/9df0936ea2d3783636a68b706594ee8aadc60827 Maybe you should update the project description, so, it says the BaseSDK must be 10.8+ Felipe.