diff --git a/dune/fufem/assemblers/istlbackend.hh b/dune/fufem/assemblers/istlbackend.hh
index bffe79f012d194d27034ab08c9a268708c12b9b6..eb114b6311a88cb5193aae21bbb41d3e227a49c4 100644
--- a/dune/fufem/assemblers/istlbackend.hh
+++ b/dune/fufem/assemblers/istlbackend.hh
@@ -184,7 +184,7 @@ private:
   //! number of multi type cols (we assume the matrix is well-formed)
   static constexpr size_t colBlocks_ = Matrix::M();
   //! 2D array of IndexSets
-  std::array<std::array<Dune::MatrixIndexSet,rowBlocks_>,colBlocks_> indices_;
+  std::array<std::array<Dune::MatrixIndexSet,colBlocks_>,rowBlocks_> indices_;
   Matrix& matrix_;
 };