After reading dave's blog I tried Is this protocol error expected? cvs -d :pserver:anonymous@anoncvs.opensource.apple.com:/cvs/root co - P WebKitTools cvs server: Updating WebKitTools U WebKitTools/ChangeLog U WebKitTools/checkout cvs server: Updating WebKitTools/DumpRenderTree U WebKitTools/DumpRenderTree/DumpRenderTree.m U WebKitTools/DumpRenderTree/DumpRenderTreePrefix.h cvs server: Updating WebKitTools/DumpRenderTree/DumpRenderTree.xcode U WebKitTools/DumpRenderTree/DumpRenderTree.xcode/.cvsignore U WebKitTools/DumpRenderTree/DumpRenderTree.xcode/project.pbxproj cvs server: Updating WebKitTools/Scripts U WebKitTools/Scripts/build-dumprendertree U WebKitTools/Scripts/build-webkit U WebKitTools/Scripts/run-safari U WebKitTools/Scripts/run-webkit-tests U WebKitTools/Scripts/update-webkit annie:~/Programming/Objective-C robert$ WebKitTools/checkout CVS root is :pserver:anonymous@anoncvs.opensource.apple.com:/cvs/root Checking out WebKitTools (again), JavaScriptCore, WebCore, WebKitLibraries, and WebKit protocol error: directory '/Network/Source/CVS/Apple/Frameworks/ JavaScriptCore' not within root '/cvs/root' =============================================================== Web Kit sources are now checked out and ready to build. You can build by projects in Xcode or with the build-webkit script. The build-webkit script is inside WebKitTools/Scripts along with other useful scripts; it's a good idea to put that directory into your shell's search path. ===============================================================