diff --git a/include/boost/config/platform/solaris.hpp b/include/boost/config/platform/solaris.hpp
index 700dc3ce..9f925666 100644
--- a/include/boost/config/platform/solaris.hpp
+++ b/include/boost/config/platform/solaris.hpp
@@ -16,6 +16,13 @@
 #define BOOST_HAS_UNISTD_H
 #include <boost/config/posix_features.hpp>
 
+//
+// pthreads don't actually work with gcc unless _PTHREADS is defined:
+//
+#if defined(__GNUC__) && defined(_POSIX_THREADS) && !defined(_PTHREADS)
+# undef BOOST_HAS_PTHREADS
+#endif
+
 
 
 
diff --git a/include/boost/config/suffix.hpp b/include/boost/config/suffix.hpp
index b57d3f1e..c0cdf71b 100644
--- a/include/boost/config/suffix.hpp
+++ b/include/boost/config/suffix.hpp
@@ -232,6 +232,8 @@
 #ifndef BOOST_HAS_THREADS
 #  undef BOOST_HAS_PTHREADS
 #  undef BOOST_HAS_PTHREAD_MUTEXATTR_SETTYPE
+#  undef BOOST_HAS_PTHREAD_YIELD
+#  undef BOOST_HAS_PTHREAD_DELAY_NP
 #  undef BOOST_HAS_WINTHREADS
 #  undef BOOST_HAS_BETHREADS
 #  undef BOOST_HAS_MPTASKS