diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7d42c61..d5fc893 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -74,7 +74,7 @@ jobs:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
   online:
-    if: '!startsWith(github.event.ref, "refs/tags/v"'
+    if: "!startsWith(github.event.ref, 'refs/tags/v')"
     needs: [docs]
     uses: OpenAstronomy/github-actions-workflows/.github/workflows/tox.yml@main
     with:
diff --git a/docs/data_types/raster.rst b/docs/data_types/raster.rst
index 0e552c3..df53248 100644
--- a/docs/data_types/raster.rst
+++ b/docs/data_types/raster.rst
@@ -103,10 +103,10 @@ Dimensions
 .. code-block:: python
 
     >>> my_rasters.raster_array_axis_physical_types
-    [('meta.obs.sequence',), (np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon'), np.str_('time')), (np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon')), (np.str_('em.wl'),)]
+    [('meta.obs.sequence',), ('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon', 'time'), ('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon'), ('em.wl',)]
 
     >>> my_rasters.sns_array_axis_physical_types
-    [(np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon'), np.str_('time')), (np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon')), (np.str_('em.wl'),)]
+    [('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon', 'time'), ('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon'), ('em.wl',)]
 
 In the raster case, ``'meta.obs.sequence'`` represents the raster scan number axis.
 For those familiar with `~ndcube.NDCubeSequence`, these are simply aliases for the `~ndcube.NDCubeSequence.array_axis_physical_axis_types` and `~ndcube.NDCubeSequence.cube_like_world_axis_physical_axis_types`, respectively.
diff --git a/docs/data_types/spectrogram.rst b/docs/data_types/spectrogram.rst
index 7240c7c..99652de 100644
--- a/docs/data_types/spectrogram.rst
+++ b/docs/data_types/spectrogram.rst
@@ -113,7 +113,9 @@ The `~sunraster.SpectrogramCube.dimensions` and `~sunraster.SpectrogramCube.arra
     >>> my_spectrograms.dimensions
     <Quantity [3., 4., 5.] pix>
     >>> my_spectrograms.array_axis_physical_types
-    [(np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon')), (np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon')), (np.str_('em.wl'),)]
+    [('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon'),
+    ('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon'),
+    ('em.wl',)]
 
 `~sunraster.SpectrogramCube.dimensions` returns a `~astropy.units.Quantity` giving the length of each dimension in pixel units while `~sunraster.SpectrogramCube.array_axis_physical_types` returns an list of tuples where each tuple contains the types of physical properties associated with each array axis.
 Since more than one physical type be associated with an array axis because they are dependent, e.g. latitude/longitude, or because of the rastering nature of the instrument, e.g. latitude/longitude and time, the length of each tuple can be greater than one.
@@ -321,7 +323,7 @@ In order to inspect the dimensionality of our sequence and the physical properti
     >>> my_sequence.dimensions
     (<Quantity 3. pix>, <Quantity 3. pix>, <Quantity 4. pix>, <Quantity 5. pix>)
     >>> my_sequence.array_axis_physical_types
-    [('meta.obs.sequence',), (np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon'), np.str_('time'), np.str_('custom:CUSTOM')), (np.str_('custom:pos.helioprojective.lat'), np.str_('custom:pos.helioprojective.lon')), (np.str_('em.wl'),)]
+    [('meta.obs.sequence',), ('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon', 'time', 'custom:CUSTOM'), ('custom:pos.helioprojective.lat', 'custom:pos.helioprojective.lon'), ('em.wl',)]
 
 Note that this is the same API as `~sunraster.SpectrogramCube` except that `sunraster.SpectrogramSequence.dimensions` returns an iterable of `~astropy.units.Quantity` objects, one for each axis.
 This is because of its inheritance from  `~ndcube.NDCubeSequence` rather than `~ndcube.NDCube`.
diff --git a/setup.cfg b/setup.cfg
index aba4cd1..4c0d7d4 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -63,8 +63,6 @@ addopts = --doctest-rst --doctest-ignore-import-errors -p no:unraisableexception
 markers =
     online: marks this test function as needing online connectivity.
 remote_data_strict = True
-doctest_subpackage_requires =
-    docs/* = ndcube<2.3.0
 filterwarnings =
     error
     # Do not fail on pytest config issues (i.e. missing plugins) but do show them