diff --git a/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/compressibleCourantNo.C b/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/compressibleCourantNo.C
index 5f04825a94..a3d68f55ca 100644
--- a/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/compressibleCourantNo.C
+++ b/applications/solvers/heatTransfer/chtMultiRegionFoam/fluid/compressibleCourantNo.C
@@ -38,7 +38,8 @@ Foam::scalar Foam::compressibleCourantNo
     scalar CoNum = 0.0;
     scalar meanCoNum = 0.0;
 
-    if (mesh.nInternalFaces())
+    //- Can have fluid domains with 0 cells so do not test.
+    //if (mesh.nInternalFaces())
     {
         surfaceScalarField SfUfbyDelta =
             mesh.surfaceInterpolation::deltaCoeffs()