diff --git a/src/mesh/interpolation/interpolation_z.cxx b/src/mesh/interpolation/interpolation_z.cxx
index 8d39e6baa8..e743ec8555 100644
--- a/src/mesh/interpolation/interpolation_z.cxx
+++ b/src/mesh/interpolation/interpolation_z.cxx
@@ -20,8 +20,10 @@
  *
  **************************************************************************/
 
+#include <bout/globals.hxx>
 #include <bout/interpolation_z.hxx>
 #include <bout/mesh.hxx>
+#include <bout/region.hxx>
 
 ZInterpolation::ZInterpolation(int y_offset, Mesh* mesh, Region<Ind3D> region_in)
     : localmesh(mesh == nullptr ? bout::globals::mesh : mesh), region(region_in),
diff --git a/tests/unit/fake_mesh.hxx b/tests/unit/fake_mesh.hxx
index 7d7326c149..4656ee0282 100644
--- a/tests/unit/fake_mesh.hxx
+++ b/tests/unit/fake_mesh.hxx
@@ -43,6 +43,9 @@ public:
     GlobalNx = nx;
     GlobalNy = ny;
     GlobalNz = nz;
+    GlobalNxNoBoundaries = nx - 2;
+    GlobalNyNoBoundaries = ny - 2;
+    GlobalNzNoBoundaries = nz;
     LocalNx = nx;
     LocalNy = ny;
     LocalNz = nz;