Segmentation error: Compiling REE on OS X 10.7 using RVM When trying to install REE using RVM on OS X Lion (10.7) you may come across the following error: /usr/bin/gcc -dynamiclib system_allocator.c -install_name @rpath/libsystem_allocator.dylib -o libsystem_allocator.dylib mkdir -p .ext/common make PREINCFLAGS='-I/opt/local/include' PRELIBS='-L/opt/local/lib -Wl,-rpath,/Users/Gavin/.rvm/rubies/ree-1.8.7-2011.03/lib -L/Users/Gavin/.rvm/rubies/ree-1.8.7-2011.03/lib -lsystem_allocator' ./ext/purelib.rb:2: [BUG] Segmentation fault ruby 1.8.7 (2011-02-18 patchlevel 334) [i686-darwin11.1.0], MBARI 0x6770, Ruby Enterprise Edition 2011.03 make: *** [.rbconfig.time] Abort trap: 6 The problem: Xcode and OS X Lion now use llvm-gcc, instead of gcc as the default compiler. The solution: Temporarily set your CC environment variable back to the old gcc: $ export CC=/usr/bin/gcc-4.2 Now try and reinstall REE passing the force argument to re-download and compile using gcc $ rvm install ree --force