diff --git a/pyproject.toml b/pyproject.toml
index 1b993cca..83586e02 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -66,6 +66,12 @@ exclude = ["tests*"]
 
 [tool.pytest.ini_options]
 addopts = "--cov=bg_atlasapi"
+filterwarnings = [
+    "error",
+]
+markers = [
+    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
+]
 
 [tool.black]
 target-version = ['py38', 'py39', 'py310', 'py311']
diff --git a/tests/test_core_atlas.py b/tests/test_core_atlas.py
index 97233546..6c60df83 100644
--- a/tests/test_core_atlas.py
+++ b/tests/test_core_atlas.py
@@ -42,14 +42,15 @@ def test_additional_ref_dict(temp_path):
     for k in ["1", "2"]:
         stack = np.ones((10, 20, 30)) * int(k)
         fake_data[k] = stack
-        tifffile.imsave(temp_path / f"{k}.tiff", stack)
+        tifffile.imwrite(temp_path / f"{k}.tiff", stack)
 
     add_ref_dict = AdditionalRefDict(fake_data.keys(), temp_path)
 
     for k, stack in add_ref_dict.items():
         assert add_ref_dict[k] == stack
 
-    assert add_ref_dict["3"] is None
+    with pytest.warns(UserWarning, match="No reference named 3"):
+        assert add_ref_dict["3"] is None
 
 
 @pytest.mark.parametrize(
diff --git a/tests/test_structure_dict.py b/tests/test_structure_dict.py
index 2f25c0d0..cd6c627b 100644
--- a/tests/test_structure_dict.py
+++ b/tests/test_structure_dict.py
@@ -33,6 +33,7 @@
 ]
 
 
+@pytest.mark.filterwarnings("ignore:No mesh filename for region root")
 def test_structure_indexing():
     structures_dict = StructuresDict(structures_list)
     print(structures_dict)