Index: fpclassify.hpp
===================================================================
--- fpclassify.hpp	(revision 46617)
+++ fpclassify.hpp	(working copy)
@@ -39,7 +39,11 @@
 
 #ifndef fpclassify
 #  if (defined(__GLIBCPP__) || defined(__GLIBCXX__)) && defined(_GLIBCXX_USE_C99_MATH) && !(defined(_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC) && (_GLIBCXX_USE_C99_FP_MACROS_DYNAMIC != 0))
+#     ifdef _STLP_VENDOR_CSTD
+#     define BOOST_FPCLASSIFY_PREFIX ::_STLP_VENDOR_CSTD::
+#     else
 #     define BOOST_FPCLASSIFY_PREFIX ::std::
+#     endif
 #  else
 #     undef BOOST_HAS_FPCLASSIFY
 #     define BOOST_FPCLASSIFY_PREFIX