diff --git a/src/mesh/parallel/fci.cxx b/src/mesh/parallel/fci.cxx
index d85f7df1e4..825eb1dfca 100644
--- a/src/mesh/parallel/fci.cxx
+++ b/src/mesh/parallel/fci.cxx
@@ -256,7 +256,7 @@ FCIMap::FCIMap(Mesh& mesh, int offset_, BoundaryRegionPar* boundary, bool zperio
 Field3D FCIMap::integrate(Field3D &f) const {
   TRACE("FCIMap::integrate");
 
-  ASSERT3(&map_mesh == f.getMesh());
+  ASSERT1(&map_mesh == f.getMesh());
 
   // Cell centre values
   Field3D centre = interp->interpolate(f);
@@ -316,6 +316,10 @@ Field3D FCIMap::integrate(Field3D &f) const {
 void FCITransform::calcYUpDown(Field3D& f) {
   TRACE("FCITransform::calcYUpDown");
 
+  // Only have forward_map/backward_map for CELL_CENTRE, so can only deal with
+  // CELL_CENTRE inputs
+  ASSERT1(f.getLocation() == CELL_CENTRE);
+
   // Ensure that yup and ydown are different fields
   f.splitYupYdown();
 
@@ -328,6 +332,10 @@ void FCITransform::calcYUpDown(Field3D& f) {
 void FCITransform::integrateYUpDown(Field3D& f) {
   TRACE("FCITransform::integrateYUpDown");
 
+  // Only have forward_map/backward_map for CELL_CENTRE, so can only deal with
+  // CELL_CENTRE inputs
+  ASSERT1(f.getLocation() == CELL_CENTRE);
+
   // Ensure that yup and ydown are different fields
   f.splitYupYdown();
 
diff --git a/src/mesh/parallel/fci.hxx b/src/mesh/parallel/fci.hxx
index 37a87a96e6..5d987c20e0 100644
--- a/src/mesh/parallel/fci.hxx
+++ b/src/mesh/parallel/fci.hxx
@@ -58,7 +58,7 @@ public:
   BoutMask corner_boundary_mask;
   
   Field3D interpolate(Field3D& f) const {
-    ASSERT3(&map_mesh == f.getMesh());
+    ASSERT1(&map_mesh == f.getMesh());
     return interp->interpolate(f);
   }
 
diff --git a/src/mesh/parallel/shiftedmetric.cxx b/src/mesh/parallel/shiftedmetric.cxx
index d6171fc117..e02fc0ba7e 100644
--- a/src/mesh/parallel/shiftedmetric.cxx
+++ b/src/mesh/parallel/shiftedmetric.cxx
@@ -146,6 +146,7 @@ const Field3D ShiftedMetric::fromFieldAligned(const Field3D &f) {
 
 const Field3D ShiftedMetric::shiftZ(const Field3D &f, const arr3Dvec &phs) const {
   ASSERT1(&mesh == f.getMesh());
+  ASSERT1(f.getLocation() == CELL_CENTRE); // only have zShift for CELL_CENTRE, so can only deal with CELL_CENTRE inputs
   if(mesh.LocalNz == 1)
     return f; // Shifting makes no difference
 
@@ -187,6 +188,9 @@ void ShiftedMetric::shiftZ(const BoutReal* in, const Array<dcomplex>& phs,
 
 void ShiftedMetric::calcYUpDown(Field3D& f) {
 
+  ASSERT1(&mesh == f.getMesh());
+  ASSERT1(f.getLocation() == CELL_CENTRE); // only have zShift for CELL_CENTRE, so can only deal with CELL_CENTRE inputs
+
   auto results = shiftZ(f, parallel_slice_phases);
 
   ASSERT3(results.size() == parallel_slice_phases.size());
@@ -248,6 +252,7 @@ ShiftedMetric::shiftZ(const Field3D& f,
 //Old approach retained so we can still specify a general zShift
 const Field3D ShiftedMetric::shiftZ(const Field3D &f, const Field2D &zangle) const {
   ASSERT1(&mesh == f.getMesh());
+  ASSERT1(f.getLocation() == zangle.getLocation());
   if(mesh.LocalNz == 1)
     return f; // Shifting makes no difference