diff --git a/devito/types/dense.py b/devito/types/dense.py
index a4ea53b699..4ae37269cb 100644
--- a/devito/types/dense.py
+++ b/devito/types/dense.py
@@ -751,8 +751,10 @@ def _C_get_field(self, region, dim, side=None):
 
     def _halo_exchange(self):
         """Perform the halo exchange with the neighboring processes."""
-        if not MPI.Is_initialized() or MPI.COMM_WORLD.size == 1 or \
-                not configuration['mpi']:
+        if not MPI.Is_initialized() or \
+                MPI.COMM_WORLD.size == 1 or \
+                not configuration['mpi'] or \
+                self.grid is None:
             # Nothing to do
             return
         if MPI.COMM_WORLD.size > 1 and self._distributor is None:
diff --git a/tests/test_tensors.py b/tests/test_tensors.py
index 815efa51ba..30ac7e578f 100644
--- a/tests/test_tensors.py
+++ b/tests/test_tensors.py
@@ -100,10 +100,10 @@ def test_tensor_matmul(func1, func2, out_type):
 
 
 @pytest.mark.parametrize('func1, func2, out_type', [
-    (VectorFunction, TensorFunction, VectorFunction),
-    (VectorTimeFunction, TensorFunction, VectorTimeFunction),
-    (VectorFunction, TensorTimeFunction, VectorTimeFunction),
-    (VectorTimeFunction, TensorTimeFunction, VectorTimeFunction)])
+    (VectorFunction, TensorFunction, TensorFunction),
+    (VectorTimeFunction, TensorFunction, TensorTimeFunction),
+    (VectorFunction, TensorTimeFunction, TensorTimeFunction),
+    (VectorTimeFunction, TensorTimeFunction, TensorTimeFunction)])
 def test_tensor_matmul_T(func1, func2, out_type):
     grid = Grid(tuple([5]*3))
     f1 = func1(name="f1", grid=grid)