[boost] [test] symbol not defined: execution_exception

When I include header <boost/test/unit_test.hpp> in my program, the linker complains that symbol "execution_exception" is undefined. I looked at the compiler output and found that class "execution_exception" is a parameter on "virtual void exception_caught(execution_exception const&)" in file test_observer.hpp. It is declared but never defined. I added "#include <boost/test/execution_monitor.hpp>" to file test_observer.hpp and the linker error went away. Is this the correct way to fix the problem? Thanks, Dave Jenkins