diff --git a/test/support/trivial.hpp b/test/support/trivial.hpp
index 77c14905..7b74597a 100644
--- a/test/support/trivial.hpp
+++ b/test/support/trivial.hpp
@@ -19,7 +19,7 @@
 #ifdef BOOST_FUSION_DETAIL_IS_TRIVIALLY_COPYABLE_CONFORMING
 #   define BOOST_FUSION_ASSERT_FALLBACK BOOST_MPL_ASSERT
 #else
-#   define BOOST_FUSION_ASSERT_FALLBACK(cond) BOOST_MPL_ASSERT((mpl::true_))
+#   define BOOST_FUSION_ASSERT_FALLBACK(cond) BOOST_MPL_ASSERT((boost::mpl::true_))
 #endif