diff --git a/src/thermophysicalModels/radiation/include/createIncompressibleRadiationModel.H b/src/thermophysicalModels/radiation/include/createIncompressibleRadiationModel.H
index ab7466d0a79195b257b3c7f38b2e301d69b14f5e..8179b675534a963f3a658655e2bfd2f3d39dde1f 100644
--- a/src/thermophysicalModels/radiation/include/createIncompressibleRadiationModel.H
+++ b/src/thermophysicalModels/radiation/include/createIncompressibleRadiationModel.H
@@ -21,12 +21,23 @@
                 runTime,
                 IOobject::MUST_READ,
                 IOobject::NO_WRITE,
-                false  // do not register!
+                false // Do not register
             )
         );
 
-        dimensionedScalar rhoRef(transportProperties.lookup("rhoRef"));
-        dimensionedScalar CpRef(transportProperties.lookup("CpRef"));
+        dimensionedScalar rhoRef
+        (
+            "rhoRef",
+            dimDensity,
+            transportProperties
+        );
+
+        dimensionedScalar CpRef
+        (
+            "CpRef",
+            dimSpecificHeatCapacity,
+            transportProperties
+        );
 
         rhoCpRef = rhoRef*CpRef;
     }