diff --git a/config/has_float128.cpp b/config/has_float128.cpp
new file mode 100644
index 0000000..60a2e2e
--- /dev/null
+++ b/config/has_float128.cpp
@@ -0,0 +1,17 @@
+//  Copyright John Maddock 2013.
+//  Use, modification and distribution are subject to the
+//  Boost Software License, Version 1.0. (See accompanying file
+//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+extern "C" {
+#include <quadmath.h>
+}
+
+int main()
+{
+   __float128 f = -2.0Q;
+   f = fabsq(f);
+
+   return 0;
+}
+