--- boost/chrono/detail/inlined/posix/thread_clock.hpp~	2011-10-10 15:27:40.000000000 -0400
+++ boost/chrono/detail/inlined/posix/thread_clock.hpp	2012-03-07 12:19:25.783089582 -0500
@@ -15,6 +15,7 @@
 #include <cassert>
 
 # include <sys/times.h>
+# include <pthread.h>
 # include <unistd.h>
 
 namespace boost { namespace chrono {