diff --git a/setup.cfg b/setup.cfg
index 8e38b0eff..60fcc2f27 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -23,8 +23,8 @@ install_requires =
     gwcs>=0.18
     asdf-astropy>=0.3
     asdf>=2.14
+    jsonschema<4.18;asdf<2.15
     ndcube>=2.0
-    jsonschema<4.18
 
 [options.extras_require]
 test =
diff --git a/specutils/io/asdf/converters.py b/specutils/io/asdf/converters.py
index e723f00e6..8e0bd15c5 100644
--- a/specutils/io/asdf/converters.py
+++ b/specutils/io/asdf/converters.py
@@ -1,6 +1,4 @@
-"""
-Contains classes that serialize spectral data types into ASDF representations.
-"""
+"""Contains classes that serialize spectral data types into ASDF representations."""
 from asdf.extension import Converter
 from asdf_astropy.converters import SpectralCoordConverter
 from astropy.nddata import (StdDevUncertainty, VarianceUncertainty,
diff --git a/specutils/io/asdf/helpers.py b/specutils/io/asdf/tests/helpers.py
similarity index 92%
rename from specutils/io/asdf/helpers.py
rename to specutils/io/asdf/tests/helpers.py
index 20aa55388..05b3ead1f 100644
--- a/specutils/io/asdf/helpers.py
+++ b/specutils/io/asdf/tests/helpers.py
@@ -1,11 +1,11 @@
 """Helpers for testing specutils objects in ASDF files.
 These are similar to those in ``asdf_astropy.testing.helpers``.
 """
-from astropy.tests.helper import assert_quantity_allclose
 from asdf_astropy.testing.helpers import assert_spectral_coord_equal
+from astropy.tests.helper import assert_quantity_allclose
 from numpy.testing import assert_allclose
 
-__all__ = ["assert_spectrum1d_equal", "assert_spectrumlist_equal"]
+__all__ = ["assert_spectral_axis_equal", "assert_spectrum1d_equal", "assert_spectrumlist_equal"]
 
 
 def assert_spectral_axis_equal(a, b):
diff --git a/specutils/io/asdf/tests/test_spectra.py b/specutils/io/asdf/tests/test_spectra.py
index cde240c94..53e592ee8 100644
--- a/specutils/io/asdf/tests/test_spectra.py
+++ b/specutils/io/asdf/tests/test_spectra.py
@@ -6,22 +6,21 @@
 from astropy.nddata import StdDevUncertainty
 
 from specutils import Spectrum1D, SpectrumList, SpectralAxis
-from specutils.io.asdf.helpers import (
+from specutils.io.asdf.tests.helpers import (
     assert_spectrum1d_equal, assert_spectrumlist_equal, assert_spectral_axis_equal)
 
 
 def create_spectrum1d(xmin, xmax, uncertainty=None):
     flux = np.ones(xmax - xmin) * u.Jy
-    wavelength = np.arange(xmin, xmax) * u.AA
+    wavelength = np.arange(xmin, xmax) * u.nm
     uncertainty = StdDevUncertainty(np.ones(xmax - xmin) * u.Jy) if uncertainty is not None else None
     return Spectrum1D(spectral_axis=wavelength, flux=flux, uncertainty=uncertainty)
 
 
 @pytest.mark.parametrize('uncertainty', [False, True])
-@pytest.mark.filterwarnings("ignore:.*The unit 'Angstrom' has been deprecated.*")
 def test_asdf_spectrum1d(tmp_path, uncertainty):
     file_path = tmp_path / "test.asdf"
-    spectrum = create_spectrum1d(5100, 5300, uncertainty=uncertainty)
+    spectrum = create_spectrum1d(510, 530, uncertainty=uncertainty)
     with asdf.AsdfFile() as af:
         af["spectrum"] = spectrum
         af.write_to(file_path)
@@ -30,10 +29,9 @@ def test_asdf_spectrum1d(tmp_path, uncertainty):
         assert_spectrum1d_equal(af["spectrum"], spectrum)
 
 
-@pytest.mark.filterwarnings("ignore:.*The unit 'Angstrom' has been deprecated.*")
 def test_asdf_spectralaxis(tmp_path):
     file_path = tmp_path / "test.asdf"
-    wavelengths  = np.arange(5100, 5300) * u.AA
+    wavelengths  = np.arange(510, 530) * u.nm
     spectral_axis = SpectralAxis(wavelengths, bin_specification="edges")
 
     with asdf.AsdfFile() as af:
@@ -44,14 +42,13 @@ def test_asdf_spectralaxis(tmp_path):
         assert_spectral_axis_equal(af["spectral_axis"], spectral_axis)
 
 
-@pytest.mark.filterwarnings("ignore:.*The unit 'Angstrom' has been deprecated.*")
 def test_asdf_spectrumlist(tmp_path):
     file_path = tmp_path / "test.asdf"
     spectra = SpectrumList([
-        create_spectrum1d(5100, 5300),
-        create_spectrum1d(5000, 5500),
-        create_spectrum1d(0, 100),
-        create_spectrum1d(1, 5)
+        create_spectrum1d(510, 530),
+        create_spectrum1d(500, 550),
+        create_spectrum1d(0, 10),
+        create_spectrum1d(0.1, 0.5)
     ])
     with asdf.AsdfFile() as af:
         af["spectrum_list"] = spectra