diff --git a/gnm/shape/gnm_data_loader_test.py b/gnm/shape/gnm_data_loader_test.py
index 4b5b15f0..843d0215 100644
--- a/gnm/shape/gnm_data_loader_test.py
+++ b/gnm/shape/gnm_data_loader_test.py
@@ -112,6 +112,17 @@ def test_load_model_from_custom_file_drops_extra_fields(self):
 
     self.assertNotIn('extra_field', data)
 
+  def test_load_model_from_custom_file_rereads_changed_file(self):
+    """A model file that changed on disk is read again, not served stale."""
+    local_path = self._write_model(joint_names=['joint1'])
+    data1 = gnm_data_loader.load_model_from_custom_file(local_path)
+
+    self._write_model(joint_names=['new_joint'])
+    data2 = gnm_data_loader.load_model_from_custom_file(local_path)
+
+    self.assertEqual(data1['joint_names'], ['joint1'])
+    self.assertEqual(data2['joint_names'], ['new_joint'])
+
   def test_load_model_from_custom_file_fails_when_file_not_found(self):
     with self.assertRaisesRegex(ValueError, 'not found'):
       gnm_data_loader.load_model_from_custom_file(
diff --git a/gnm/shape/gnm_utils_test.py b/gnm/shape/gnm_utils_test.py
index ff8237e6..cbac4df8 100644
--- a/gnm/shape/gnm_utils_test.py
+++ b/gnm/shape/gnm_utils_test.py
@@ -42,7 +42,10 @@ class BaseGNMUtilsTest(parameterized.TestCase):
   """Base class loading the GNMs on demand.
 
   Attributes:
-    gnms: The GNMs, by version and variant.
+    gnms: The GNMs, by version and variant. Loaded models are shared by the
+      tests of a class, so tests must not modify them (neither in place nor by
+      reassigning attributes). Copy a model with `copy.deepcopy(...)` before
+      changing it.
     max_loaded: The maximum number of models kept in memory at once, e.g. 2 for
       tests using two models at once. If None, all the models of a version are
       kept in memory.
diff --git a/gnm/shape/oss_data_loaders/oss_data_loaders_test.py b/gnm/shape/oss_data_loaders/oss_data_loaders_test.py
index 7c3e1d40..d1de35bb 100644
--- a/gnm/shape/oss_data_loaders/oss_data_loaders_test.py
+++ b/gnm/shape/oss_data_loaders/oss_data_loaders_test.py
@@ -246,6 +246,8 @@ def test_load_model_from_remote_returns_independent_data(self):
         gnm_specs.GNMVariant.HEAD,
         cache_dir=self.temp_dir,
     )
+    expected_positions = np.array(data1['template_vertex_positions'])
+    data1['template_vertex_positions'][:] = 1.0
     data1['joint_names'].append('leaked_joint')
     data2 = oss_data_loaders.load_model_from_remote(
         gnm_specs.GNMMajorVersion.V3,
@@ -254,6 +256,9 @@ def test_load_model_from_remote_returns_independent_data(self):
     )
 
     self.assertIsNot(data1, data2)
+    np.testing.assert_array_equal(
+        data2['template_vertex_positions'], expected_positions
+    )
     self.assertNotIn('leaked_joint', data2['joint_names'])
 
   def test_load_model_from_remote_with_str_cache_dir(self):