diff --git a/dune/common/fmatrix.hh b/dune/common/fmatrix.hh
index 42c379ea9c3612675b716722eec61df3f22a10a6..59d3db71ba896351f6796e77333da38abc58eb04 100644
--- a/dune/common/fmatrix.hh
+++ b/dune/common/fmatrix.hh
@@ -163,7 +163,7 @@ namespace Dune
     template<typename T>
     FieldMatrix& operator=(const FieldMatrix<T, ROWS, COLS>& x)
     {
-      _data = x._data;
+      std::copy(x.begin(), x.end(), this->begin());
       return *this;
     }