diff --git a/tests/tests.yaml b/tests/tests.yaml
index 5ffa437ed37..49a5915f6f7 100644
--- a/tests/tests.yaml
+++ b/tests/tests.yaml
@@ -138,7 +138,7 @@ answer_tests:
     - yt/frontends/boxlib/tests/test_outputs.py:test_units_override
     - yt/frontends/boxlib/tests/test_outputs.py:test_raw_fields
 
-  local_boxlib_particles_008:
+  local_boxlib_particles_009:
     - yt/frontends/boxlib/tests/test_outputs.py:test_LyA
     - yt/frontends/boxlib/tests/test_outputs.py:test_nyx_particle_io
     - yt/frontends/boxlib/tests/test_outputs.py:test_castro_particle_io
diff --git a/yt/frontends/boxlib/data_structures.py b/yt/frontends/boxlib/data_structures.py
index 7c7bd57d525..77a6da6aa3e 100644
--- a/yt/frontends/boxlib/data_structures.py
+++ b/yt/frontends/boxlib/data_structures.py
@@ -751,9 +751,9 @@ def _parse_cparams(self):
                 # domain_dimensions to have three elements, with 1 in the additional
                 # slots if we're not in 3D, so append them as necessary.
 
-                if len(vals) == 1:
+                if self.dimensionality == 1:
                     vals = self.domain_dimensions = np.array([vals[0], 1, 1])
-                elif len(vals) == 2:
+                elif self.dimensionality == 2:
                     vals = self.domain_dimensions = np.array([vals[0], vals[1], 1])
             elif param == "amr.ref_ratio":
                 vals = self.refine_by = int(vals[0])