Index: uspace/lib/cpp/include/impl/iosfwd.hpp
===================================================================
--- uspace/lib/cpp/include/impl/iosfwd.hpp	(revision 6648ab33d956d82634fb7b457a8e08f19ed97c77)
+++ uspace/lib/cpp/include/impl/iosfwd.hpp	(revision 5209fd7121f8fca1bdba19f033c9262422c2599b)
@@ -26,4 +26,7 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+
+#ifndef LIBCPP_IOSFWD
+#define LIBCPP_IOSFWD
 
 namespace std
@@ -155,2 +158,4 @@
     using streamoff = long long;
 }
+
+#endif