diff --git a/dumux/porousmediumflow/nonisothermal/implicit/model.hh b/dumux/porousmediumflow/nonisothermal/implicit/model.hh
index 2e9262565ecd9353b25bc1f87b578ebb7e31e87f..22c4a0fd48e4fbf8e3e26dc4e90aea91c85bb7f1 100644
--- a/dumux/porousmediumflow/nonisothermal/implicit/model.hh
+++ b/dumux/porousmediumflow/nonisothermal/implicit/model.hh
@@ -55,7 +55,7 @@ public:
     static void maybeAddTemperature(VtkOutputModule& vtkOutputModule)
     {
         // register vtk output field for temperature
-        vtkOutputModule.addPrimaryVariable("temperature", Indices::temperatureIdx);
+        vtkOutputModule.addVolumeVariable([](const auto& volVars){ return volVars.temperature(); }, "temperature");
     }
 };