```
brew install valkyrie --verbose
==> Downloading http://valgrind.org/downloads/valkyrie-2.0.0.tar.bz2
Already downloaded: /Library/Caches/Homebrew/valkyrie-2.0.0.tar.bz2
==> Verifying valkyrie-2.0.0.tar.bz2 checksum
tar xf /Library/Caches/Homebrew/valkyrie-2.0.0.tar.bz2
==> qmake PREFIX=/usr/local/Cellar/valkyrie/2.0.0
==> make install
cd src/ && /usr/local/opt/qt/bin/qmake /private/tmp/valkyrie-Rw69/valkyrie-2.0.0/src/src.pro PREFIX=/usr/local/Cellar/valkyrie/2.0.0 -o Makefile
cd src/ && /Applications/Xcode.app/Contents/Developer/usr/bin/make -f Makefile install
compiling main.cpp
compiling mainwindow.cpp
compiling help/help_about.cpp
compiling help/help_context.cpp
compiling help/help_handbook.cpp
compiling help/help_urls.cpp
compiling objects/helgrind_object.cpp
compiling objects/memcheck_object.cpp
compiling objects/tool_object.cpp
compiling objects/valkyrie_object.cpp
compiling objects/valgrind_object.cpp
compiling objects/vk_objects.cpp
objects/tool_object.cpp:391:7: error: use of undeclared identifier 'usleep'
      usleep( WAIT_VG_START_SLEEP * 1000 );
      ^
objects/tool_object.cpp:474:13: error: use of undeclared identifier 'usleep'
            usleep( 1000 * sleepDuration );
            ^
2 errors generated.
make[1]: *** [obj/tool_object.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [sub-src-install_subtargets] Error 2
```