diff --git a/applications/solvers/compressible/rhoCentralFoam/BCs/U/maxwellSlipUFvPatchVectorField.C b/applications/solvers/compressible/rhoCentralFoam/BCs/U/maxwellSlipUFvPatchVectorField.C
index 07896a6e6c..765dd666ce 100644
--- a/applications/solvers/compressible/rhoCentralFoam/BCs/U/maxwellSlipUFvPatchVectorField.C
+++ b/applications/solvers/compressible/rhoCentralFoam/BCs/U/maxwellSlipUFvPatchVectorField.C
@@ -104,12 +104,17 @@ maxwellSlipUFvPatchVectorField::maxwellSlipUFvPatchVectorField
             vectorField("value", dict, p.size())
         );
 
-        this->refValue() = vectorField("refValue", dict, p.size());
-        this->valueFraction() = scalarField("valueFraction", dict, p.size());
-    }
-    else
-    {
-        mixedFixedValueSlipFvPatchVectorField::evaluate();
+        if (dict.found("refValue") && dict.found("valueFraction"))
+        {
+            this->refValue() = vectorField("refValue", dict, p.size());
+            this->valueFraction() = 
+                scalarField("valueFraction", dict, p.size());
+        }
+        else
+        {
+            this->refValue() = *this;
+            this->valueFraction() = scalar(1.0);
+        }
     }
 }