diff --git a/foolbox/models/base.py b/foolbox/models/base.py
index 6a207bb2..3336aef3 100644
--- a/foolbox/models/base.py
+++ b/foolbox/models/base.py
@@ -66,7 +66,7 @@ def _preprocess(self, inputs: ep.TensorType) -> ep.TensorType:
 
     @property
     def data_format(self) -> Any:
-        return getattr(self._model, "data_format", None)
+        return self._model.data_format  # type: ignore
 
 
 ModelType = TypeVar("ModelType", bound="ModelWithPreprocessing")
diff --git a/tests/test_attacks_base.py b/tests/test_attacks_base.py
index 41bc085a..16e6fead 100644
--- a/tests/test_attacks_base.py
+++ b/tests/test_attacks_base.py
@@ -45,21 +45,3 @@ class Model:
     model.data_format = "invalid"  # type: ignore
     with pytest.raises(ValueError):
         assert fbn.attacks.base.get_channel_axis(model, 3)  # type: ignore
-
-
-def test_transform_bounds_wrapper_data_format() -> None:
-    class Model(fbn.models.Model):
-        data_format = "channels_first"
-
-        @property
-        def bounds(self) -> fbn.types.Bounds:
-            return fbn.types.Bounds(0, 1)
-
-        def __call__(self, inputs: fbn.models.base.T) -> fbn.models.base.T:
-            return inputs
-
-    model = Model()
-    wrapped_model = fbn.models.TransformBoundsWrapper(model, (0, 1))
-    assert fbn.attacks.base.get_channel_axis(
-        model, 3
-    ) == fbn.attacks.base.get_channel_axis(wrapped_model, 3)
diff --git a/tests/test_models.py b/tests/test_models.py
index 49f56736..e41a0b91 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -234,3 +234,38 @@ def test_preprocessing(fmodel_and_data: ModelAndData) -> None:
         fmodel = fbn.models.base.ModelWithPreprocessing(
             fmodel._model, fmodel.bounds, fmodel.dummy, preprocessing
         )
+
+
+def test_transform_bounds_wrapper_data_format() -> None:
+    class Model(fbn.models.Model):
+        data_format = "channels_first"
+
+        @property
+        def bounds(self) -> fbn.types.Bounds:
+            return fbn.types.Bounds(0, 1)
+
+        def __call__(self, inputs: fbn.models.base.T) -> fbn.models.base.T:
+            return inputs
+
+    model = Model()
+    wrapped_model = fbn.models.TransformBoundsWrapper(model, (0, 1))
+    assert fbn.attacks.base.get_channel_axis(
+        model, 3
+    ) == fbn.attacks.base.get_channel_axis(wrapped_model, 3)
+    assert hasattr(wrapped_model, "data_format")
+    assert not hasattr(wrapped_model, "not_data_format")
+
+
+def test_transform_bounds_wrapper_missing_data_format() -> None:
+    class Model(fbn.models.Model):
+        @property
+        def bounds(self) -> fbn.types.Bounds:
+            return fbn.types.Bounds(0, 1)
+
+        def __call__(self, inputs: fbn.models.base.T) -> fbn.models.base.T:
+            return inputs
+
+    model = Model()
+    wrapped_model = fbn.models.TransformBoundsWrapper(model, (0, 1))
+    assert not hasattr(wrapped_model, "data_format")
+    assert not hasattr(wrapped_model, "not_data_format")