diff --git a/data/misc/diff_missing_fill.nc b/data/misc/diff_missing_fill.nc
new file mode 100644
index 0000000..74e0e48
Binary files /dev/null and b/data/misc/diff_missing_fill.nc differ
diff --git a/tests/conftest.py b/tests/conftest.py
index 0e91cae..624df0c 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -130,6 +130,12 @@ def sample_cordex_path(data_dir: Path) -> Path:
     )
 
 
+@pytest.fixture
+def sample_incoherent_encoding_path(data_dir: Path) -> Path:
+    """Return path to a incoherent NetCDF file."""
+    return data_dir / "misc/diff_missing_fill.nc"
+
+
 def pytest_configure(config):
     """Register custom markers."""
     config.addinivalue_line(
diff --git a/tests/test_entrypoint.py b/tests/test_entrypoint.py
index b1aef6d..7768ac1 100644
--- a/tests/test_entrypoint.py
+++ b/tests/test_entrypoint.py
@@ -214,6 +214,25 @@ def test_xarray_open_with_freva_engine(self, sample_netcdf_path: Path):
         assert isinstance(ds, xr.Dataset)
         ds.close()
 
+    @pytest.mark.required_data
+    def test_decoding(self, sample_incoherent_encoding_path: Path):
+        with pytest.warns():
+            ds = xr.open_dataset(str(sample_incoherent_encoding_path), engine="prism")
+            assert isinstance(ds, xr.Dataset)
+            ds.close()
+
+    @pytest.mark.required_data
+    def test_not_decoding(self, sample_incoherent_encoding_path: Path):
+        import warnings
+
+        with warnings.catch_warnings():
+            warnings.simplefilter("error")
+            ds = xr.open_dataset(
+                str(sample_incoherent_encoding_path), engine="prism", decode_cf=False
+            )
+            assert isinstance(ds, xr.Dataset)
+            ds.close()
+
 
 class TestCustomRegistry:
     """Tests for custom backend registration."""