diff --git a/docs/users_guide/ffi-chap.xml b/docs/users_guide/ffi-chap.xml
index c124ddba0e1b5c1adfae1cabe32b0a530c4eceed..47c0f01ba98326a8428d3f9e4e2d3f0a571273e3 100644
--- a/docs/users_guide/ffi-chap.xml
+++ b/docs/users_guide/ffi-chap.xml
@@ -651,7 +651,7 @@ int main(int argc, char *argv[])
       <title>Floating point and the FFI</title>
 
       <para>
-        On POSIX systems, the <literal>fenv.h</literal> header
+        The standard C99 <literal>fenv.h</literal> header
         provides operations for inspecting and modifying the state of
         the floating point unit.  In particular, the rounding mode
         used by floating point operations can be changed, and the