diff --git a/src/finiteVolume/fields/fvPatchFields/derived/fixedFluxPressure/fixedFluxPressureFvPatchScalarField.C b/src/finiteVolume/fields/fvPatchFields/derived/fixedFluxPressure/fixedFluxPressureFvPatchScalarField.C
index 0b330ec9cd..7c2da576c9 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/fixedFluxPressure/fixedFluxPressureFvPatchScalarField.C
+++ b/src/finiteVolume/fields/fvPatchFields/derived/fixedFluxPressure/fixedFluxPressureFvPatchScalarField.C
@@ -86,15 +86,26 @@ Foam::fixedFluxPressureFvPatchScalarField::fixedFluxPressureFvPatchScalarField
     gradient().map(ptf.gradient(), mapper);
 
     // Evaluate the value field from the gradient if the internal field is valid
-    if (notNull(iF) && iF.size())
+    if (notNull(iF))
     {
-        scalarField::operator=
-        (
-            //patchInternalField() + gradient()/patch().deltaCoeffs()
-            // ***HGW Hack to avoid the construction of mesh.deltaCoeffs
-            // which fails for AMI patches for some mapping operations
-            patchInternalField() + gradient()*(patch().nf() & patch().delta())
-        );
+        if (iF.size())
+        {
+            // Note: cannot ask for nf() if zero faces
+
+            scalarField::operator=
+            (
+                //patchInternalField() + gradient()/patch().deltaCoeffs()
+                // ***HGW Hack to avoid the construction of mesh.deltaCoeffs
+                // which fails for AMI patches for some mapping operations
+                patchInternalField()
+              + gradient()*(patch().nf() & patch().delta())
+            );
+        }
+    }
+    else
+    {
+        // Enforce mapping of values so we have a valid starting value
+        this->map(ptf, mapper);
     }
 }