diff --git a/src/amdis/common/FieldMatVec.hpp b/src/amdis/common/FieldMatVec.hpp
index add4197777bcb07de4f533a28834c195d936b45b..6a316262b4e16a8e517d4989c385dd73190378fc 100644
--- a/src/amdis/common/FieldMatVec.hpp
+++ b/src/amdis/common/FieldMatVec.hpp
@@ -197,6 +197,9 @@ namespace Dune
   template <class T, int M, int N>
   FieldMatrix<T,N,M> trans(FieldMatrix<T, M, N> const& A);
 
+  template <class T, int M, int N>
+  FieldMatrix<T,M,N> operator-(FieldMatrix<T, M, N> A);
+
 
   template <class T, int M, int N, class S,
     std::enable_if_t<std::is_convertible<S,T>::value, int> = 0>
diff --git a/src/amdis/common/FieldMatVec.inc.hpp b/src/amdis/common/FieldMatVec.inc.hpp
index c0d5641005f96b1efb580f8868945ddb28d0a4a8..cadb8d3a551bc7a2d6f61d281880585f7b64f964 100644
--- a/src/amdis/common/FieldMatVec.inc.hpp
+++ b/src/amdis/common/FieldMatVec.inc.hpp
@@ -349,6 +349,11 @@ FieldMatrix<T,N,M> trans(FieldMatrix<T, M, N> const& A)
   return At;
 }
 
+template <class T, int M, int N>
+FieldMatrix<T,M,N> operator-(FieldMatrix<T,M,N> A)
+{
+  return A *= -1;
+}
 
 template <class T, int M, int N, class S,
   std::enable_if_t<std::is_convertible<S,T>::value, int>>