gistfile1.diff

diff --git a/python/firedrake/solving.py b/python/firedrake/solving.py
index 4480426..cb01c61 100644
--- a/python/firedrake/solving.py
+++ b/python/firedrake/solving.py
@@ -471,11 +471,11 @@ def _assemble(f, tensor=None, bcs=None):
                         op2.INC, (test.interior_facet_node_map(bcs)[op2.i[0]],
                                   trial.interior_facet_node_map(bcs)[
                                       op2.i[1]]),
-                        flatten=True)
+                        flatten=has_vec_fs(test))
                 elif is_vec:
                     tensor_arg = tensor(
                         op2.INC, test.interior_facet_node_map()[op2.i[0]],
-                        flatten=True)
+                        flatten=has_vec_fs(test))
                 else:
                     tensor_arg = tensor(op2.INC)
                 args = [kernel, m.interior_facets.set, tensor_arg,
@@ -483,7 +483,7 @@ def _assemble(f, tensor=None, bcs=None):
                                    flatten=True)]
                 for c in fd.original_coefficients:
                     args.append(c.dat(op2.READ, c.interior_facet_node_map(),
-                                      flatten=True))
+                                      flatten=has_vec_fs(c)))
                 args.append(m.interior_facets.local_facet_dat(op2.READ))
                 op2.par_loop(*args)