diff --git a/gerbonara/apertures.py b/gerbonara/apertures.py
index 33b78df..0a4bf37 100644
--- a/gerbonara/apertures.py
+++ b/gerbonara/apertures.py
@@ -17,7 +17,7 @@
 #
 
 import math
-from dataclasses import dataclass, replace, field, fields, InitVar, KW_ONLY
+from dataclasses import dataclass, replace, field, fields, InitVar
 
 from .aperture_macros.parse import GenericMacros
 from .utils import MM, Inch
@@ -60,16 +60,26 @@ class Length:
 @dataclass
 class Aperture:
     """ Base class for all apertures. """
-    _ : KW_ONLY
-    #: :py:class:`gerbonara.utils.LengthUnit` used for all length fields of this aperture.
-    unit : str = None
-    #: GerberX2 attributes of this aperture. Note that this will only contain aperture attributes, not file attributes.
-    #: File attributes are stored in the :py:attr:`~.GerberFile.attrs` of the :py:class:`.GerberFile`.
-    attrs : dict = field(default_factory=dict)
-    #: Aperture index this aperture had when it was read from the Gerber file. This field is purely informational since
-    #: apertures are de-duplicated and re-numbered when writing a Gerber file. For `D10`, this field would be `10`. When
-    #: you programmatically create a new aperture, you do not have to set this.
-    original_number : int = None
+
+    # hackety hack: Work around python < 3.10 not having dataclasses.KW_ONLY.
+    # 
+    # For details, refer to graphic_objects.py
+    def __init_subclass__(cls):
+        #: :py:class:`gerbonara.utils.LengthUnit` used for all length fields of this aperture.
+        cls.unit = None
+        #: GerberX2 attributes of this aperture. Note that this will only contain aperture attributes, not file attributes.
+        #: File attributes are stored in the :py:attr:`~.GerberFile.attrs` of the :py:class:`.GerberFile`.
+        cls.attrs = field(default_factory=dict)
+        #: Aperture index this aperture had when it was read from the Gerber file. This field is purely informational since
+        #: apertures are de-duplicated and re-numbered when writing a Gerber file. For `D10`, this field would be `10`. When
+        #: you programmatically create a new aperture, you do not have to set this.
+        cls.original_number = None
+
+        d = {'unit': str, 'attrs': dict, 'original_number': int}
+        if hasattr(cls, '__annotations__'):
+            cls.__annotations__.update(d)
+        else:
+            cls.__annotations__ = d
 
     @property
     def hole_shape(self):
diff --git a/gerbonara/graphic_objects.py b/gerbonara/graphic_objects.py
index 3136b39..35c08f3 100644
--- a/gerbonara/graphic_objects.py
+++ b/gerbonara/graphic_objects.py
@@ -18,7 +18,7 @@
 
 import math
 import copy
-from dataclasses import dataclass, KW_ONLY, astuple, replace, field, fields
+from dataclasses import dataclass, astuple, replace, field, fields
 
 from .utils import MM, InterpMode, to_unit, rotate_point
 from . import graphic_primitives as gp
@@ -45,6 +45,8 @@ class GraphicObject:
 
     # hackety hack: Work around python < 3.10 not having dataclasses.KW_ONLY. Once we drop python 3.8 and 3.9, we can
     # get rid of this, just set these as normal fields, and decorate GraphicObject with @dataclass.
+    # 
+    # See also: apertures.py, graphic_primitives.py
     def __init_subclass__(cls):
         #: bool representing the *color* of this feature: whether this is a *dark* or *clear* feature. Clear and dark are
         #: meant in the sense that they are used in the Gerber spec and refer to whether the transparency film that this
@@ -61,7 +63,11 @@ class GraphicObject:
         #: which are stored in the :py:class:`.GerberFile` object instead.
         cls.attrs = field(default_factory=dict)
 
-        cls.__annotations__.update({'polarity_dark' : bool, 'unit' : str, 'attrs': dict})
+        d = {'polarity_dark' : bool, 'unit' : str, 'attrs': dict}
+        if hasattr(cls, '__annotations__'):
+            cls.__annotations__.update(d)
+        else:
+            cls.__annotations__ = d
 
 
     def converted(self, unit):
diff --git a/gerbonara/graphic_primitives.py b/gerbonara/graphic_primitives.py
index dd421a7..072a98a 100644
--- a/gerbonara/graphic_primitives.py
+++ b/gerbonara/graphic_primitives.py
@@ -19,7 +19,7 @@
 import math
 import itertools
 
-from dataclasses import dataclass, KW_ONLY, replace
+from dataclasses import dataclass, replace
 
 from .utils import *
 
@@ -28,8 +28,18 @@ prec = lambda x: f'{float(x):.6}'
 
 @dataclass
 class GraphicPrimitive:
-    _ : KW_ONLY
-    polarity_dark : bool = True
+
+    # hackety hack: Work around python < 3.10 not having dataclasses.KW_ONLY.
+    # 
+    # For details, refer to graphic_objects.py
+    def __init_subclass__(cls):
+        cls.polarity_dark = True
+
+        d = {'polarity_dark': bool}
+        if hasattr(cls, '__annotations__'):
+            cls.__annotations__.update(d)
+        else:
+            cls.__annotations__ = d
 
     def bounding_box(self):
         """ Return the axis-aligned bounding box of this feature.
diff --git a/gerbonara/ipc356.py b/gerbonara/ipc356.py
index 06a87f0..435a805 100644
--- a/gerbonara/ipc356.py
+++ b/gerbonara/ipc356.py
@@ -23,7 +23,7 @@ import math
 import re
 from enum import Enum
 import warnings
-from dataclasses import dataclass, KW_ONLY
+from dataclasses import dataclass
 from pathlib import Path
 
 from .cam import CamFile, FileSettings
@@ -414,7 +414,6 @@ class TestRecord:
     rotation : float = 0
     solder_mask : SoldermaskInfo = None
     lefover : str = None
-    _ : KW_ONLY
     unit : LengthUnit = None
 
     def __str__(self):
@@ -563,7 +562,6 @@ def format_coord_chain(line, settings, coords, cont, unit):
 class Outline:
     outline_type : OutlineType
     outline : [(float,)]
-    _ : KW_ONLY
     unit : LengthUnit = None
 
     @classmethod
@@ -596,7 +594,6 @@ class Conductor:
     layer : int
     aperture : (float,)
     coords : [(float,)]
-    _ : KW_ONLY
     unit : LengthUnit = None
 
     @classmethod
diff --git a/run-tests.sh b/run-tests.sh
index 1ed2b66..996c1e7 100755
--- a/run-tests.sh
+++ b/run-tests.sh
@@ -24,7 +24,7 @@ mkdir -p podman/testdata/git
 git ls-tree --full-tree -r HEAD --name-only | rsync -lptgoDv --delete . --files-from - podman/testdata/git/
 #git clone --depth 1 . podman/testdata/git
 
-for distro in ubuntu arch
+for distro in ubuntu-old ubuntu arch
 do
     podman build $NO_CACHE -t gerbonara-$distro-testenv -f podman/$distro-testenv
     mkdir -p /tmp/gerbonara-test-out