diff --git a/dune/codegen/sumfact/transposereg.hh b/dune/codegen/sumfact/transposereg.hh
index 7a1ac55f9eb9aa97b968e5d9f4d33cfe1a0c8079..4bb5c16c85944a75ee26fe7a764dfd4376021e4a 100644
--- a/dune/codegen/sumfact/transposereg.hh
+++ b/dune/codegen/sumfact/transposereg.hh
@@ -6,7 +6,7 @@
 // DOUBLE 2 x 2
 void transpose_reg(Vec2d& a0, Vec2d& a1)
 {
-  double tmp = a0[1];
+  auto tmp = a0[1];
   a0 = Vec2d(a0[0], a1[0]);
   a1 = Vec2d(tmp, a1[1]);
 }