diff --git a/src/thermophysicalModels/radiation/derivedFvPatchFields/greyDiffusiveRadiation/greyDiffusiveRadiationMixedFvPatchScalarField.C b/src/thermophysicalModels/radiation/derivedFvPatchFields/greyDiffusiveRadiation/greyDiffusiveRadiationMixedFvPatchScalarField.C
index d475f96c6b..98906aac4b 100644
--- a/src/thermophysicalModels/radiation/derivedFvPatchFields/greyDiffusiveRadiation/greyDiffusiveRadiationMixedFvPatchScalarField.C
+++ b/src/thermophysicalModels/radiation/derivedFvPatchFields/greyDiffusiveRadiation/greyDiffusiveRadiationMixedFvPatchScalarField.C
@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011-2017 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2018 OpenFOAM Foundation
      \\/     M anipulation  | Copyright (C) 2016 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
@@ -145,10 +145,7 @@ updateCoeffs()
     const scalarField& Tp =
         patch().lookupPatchField<volScalarField, scalar>(TName_);
 
-    const radiationModel& radiation =
-        db().lookupObject<radiationModel>("radiationProperties");
-
-    const fvDOM& dom(refCast<const fvDOM>(radiation));
+    const fvDOM& dom = db().lookupObject<fvDOM>("radiationProperties");
 
     label rayId = -1;
     label lambdaId = -1;
@@ -202,7 +199,7 @@ updateCoeffs()
     {
         Ir += patch().lookupPatchField<volScalarField,scalar>
         (
-            radiation.externalRadHeatFieldName_
+            dom.externalRadHeatFieldName_
         );
     }