Fix compilation on Mac OS X 10.9.3 (Xcode 5.1.1)

Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Merge pull request #3 from nwatkiss/fix-macosx-10.9.3

Fix compilation on Mac OS X 10.9.3 (Xcode 5.1.1)