diff --git a/dune/common/bigunsignedint.hh b/dune/common/bigunsignedint.hh
index e3f4b1b8fc469365b45e4cd6ecede474e225e64b..18e7d7d24eb0157861e70309838ed3c927578cf1 100644
--- a/dune/common/bigunsignedint.hh
+++ b/dune/common/bigunsignedint.hh
@@ -146,7 +146,7 @@ namespace Dune
   private:
     unsigned short digit[n];
 #if HAVE_MPI
-    friend class MPITraits<bigunsignedint<k> >;
+    friend struct MPITraits<bigunsignedint<k> >;
 #endif
     inline void assign(std::size_t x);