diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 0b849bc..ccd55b2 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -91,7 +91,7 @@ jobs:
     - name: Run docexamples
       if: ${{ matrix.openmm == 'true' }}
       run: |
-        pytest --doctest-modules $PYTEST_ARGS $COV openff
+        pytest --doctest-modules $PYTEST_ARGS $COV openff --ignore=openff/units/tests
 
     - name: Codecov
       uses: codecov/codecov-action@v1
diff --git a/devtools/conda-envs/docs_env.yaml b/devtools/conda-envs/docs_env.yaml
index 3df6bac..3393797 100644
--- a/devtools/conda-envs/docs_env.yaml
+++ b/devtools/conda-envs/docs_env.yaml
@@ -5,7 +5,7 @@ dependencies:
   - python
   - pip
   - numpy
-  - pint =0.19
+  - pint >=0.20.1
   - openff-utilities >=0.1.3
   - sphinx >=4.5,<5
   - myst-parser>=0.13.6
diff --git a/devtools/conda-envs/test_env.yaml b/devtools/conda-envs/test_env.yaml
index 40d86a7..01b6853 100644
--- a/devtools/conda-envs/test_env.yaml
+++ b/devtools/conda-envs/test_env.yaml
@@ -6,7 +6,7 @@ dependencies:
   - python
   - pip
   - numpy
-  - pint =0.19
+  - pint >=0.20.1
   - openff-utilities >=0.1.3
 
     # Tests
diff --git a/openff/units/__init__.py b/openff/units/__init__.py
index 196a006..c459025 100644
--- a/openff/units/__init__.py
+++ b/openff/units/__init__.py
@@ -1,8 +1,12 @@
-from pint import UnitRegistry
-
 from openff.units._version import get_versions  # type: ignore
 from openff.units.openmm import ensure_quantity
-from openff.units.units import DEFAULT_UNIT_REGISTRY, Measurement, Quantity, Unit
+from openff.units.units import (
+    DEFAULT_UNIT_REGISTRY,
+    Measurement,
+    Quantity,
+    Unit,
+    UnitRegistry,
+)
 
 __all__ = [
     "unit",
diff --git a/openff/units/data/defaults.txt b/openff/units/data/defaults.txt
index 050eb85..a978d67 100644
--- a/openff/units/data/defaults.txt
+++ b/openff/units/data/defaults.txt
@@ -109,7 +109,8 @@ hertz = 1 / second = Hz
 reciprocal_centimeter = 1 / cm = cm_1 = kayser
 
 # Velocity
-[velocity] = [length] / [time] = [speed]
+# As of 0.20, derived dimensions cannot have aliases
+[velocity] = [length] / [time]
 
 # Acceleration
 [acceleration] = [velocity] / [time]
diff --git a/openff/units/elements.py b/openff/units/elements.py
index 29ee4e8..29b55b5 100644
--- a/openff/units/elements.py
+++ b/openff/units/elements.py
@@ -36,7 +36,7 @@
     "SYMBOLS",
 ]
 
-MASSES: Dict[int, Quantity[float]] = {
+MASSES: Dict[int, Quantity] = {
     index + 1: Quantity(mass, unit.dalton)
     for index, mass in enumerate(
         [
diff --git a/openff/units/openmm.py b/openff/units/openmm.py
index 18c7236..b83b89a 100644
--- a/openff/units/openmm.py
+++ b/openff/units/openmm.py
@@ -211,6 +211,8 @@ def to_openmm_inner(quantity) -> "openmm_unit.Quantity":
 
         return value * openmm_unit_
 
+    assert isinstance(quantity, Quantity)
+
     try:
         return to_openmm_inner(quantity)
     except MissingOpenMMUnitError:
@@ -262,7 +264,7 @@ def _ensure_openff_quantity(
             )
     else:
         try:
-            return unit.Quantity(  # type: ignore
+            return unit.Quantity(
                 unknown_quantity,
                 unit.dimensionless,
             )
diff --git a/openff/units/tests/test_units.py b/openff/units/tests/test_units.py
index 9074ffe..b07cad2 100644
--- a/openff/units/tests/test_units.py
+++ b/openff/units/tests/test_units.py
@@ -36,14 +36,14 @@ def test_pickle_unit(self):
 
         assert x == y
 
-    def test_pick_quantity(self):
+    def test_pickle_quantity(self):
         x = 1.0 * unit.kelvin
         y = pickle.loads(pickle.dumps(x))
 
         assert x == y
 
     @skip_if_missing("uncertainties")
-    def test_pickle_quantity(self):
+    def test_pickle_quantity_uncertainties(self):
         x = (1.0 * unit.kelvin).plus_minus(0.05)
         y = pickle.loads(pickle.dumps(x))
 
diff --git a/openff/units/units.py b/openff/units/units.py
index 30cabfa..4ca257d 100644
--- a/openff/units/units.py
+++ b/openff/units/units.py
@@ -1,16 +1,16 @@
 """
 Core classes for OpenFF Units
 """
-
 import uuid
 import warnings
-from typing import TYPE_CHECKING, TypeVar
+from typing import TYPE_CHECKING
 
 import pint
 from openff.utilities import requires_package
-from pint.measurement import _Measurement
-from pint.quantity import _Quantity
-from pint.unit import _Unit
+from pint import Measurement as _Measurement
+from pint import Quantity as _Quantity
+from pint import Unit as _Unit
+from pint import UnitRegistry as _UnitRegistry
 
 from openff.units.utilities import get_defaults_path
 
@@ -24,45 +24,16 @@
     "Unit",
 ]
 
-DEFAULT_UNIT_REGISTRY = pint.UnitRegistry(get_defaults_path())
-"""The default unit registry provided by OpenFF Units"""
-
-
-def _unpickle_quantity(cls, *args):
-    """Rebuild quantity upon unpickling using the application registry."""
-    return pint._unpickle(DEFAULT_UNIT_REGISTRY.Quantity, *args)
-
-
-def _unpickle_unit(cls, *args):
-    """Rebuild unit upon unpickling using the application registry."""
-    return pint._unpickle(DEFAULT_UNIT_REGISTRY.Unit, *args)
-
-
-def _unpickle_measurement(cls, *args):
-    """Rebuild measurement upon unpickling using the application registry."""
-    return pint._unpickle(DEFAULT_UNIT_REGISTRY.Measurement, *args)
-
 
 class Unit(_Unit):
     """A unit of measure."""
 
-    _REGISTRY = DEFAULT_UNIT_REGISTRY
-
-    def __reduce__(self):
-        return _unpickle_unit, (Unit, self._units)
+    pass
 
 
-_MagnitudeType = TypeVar("_MagnitudeType")
-
-
-class Quantity(_Quantity[_MagnitudeType]):
+class Quantity(_Quantity):
     """A value with associated units."""
 
-    _REGISTRY = DEFAULT_UNIT_REGISTRY
-
-    def __reduce__(self):
-        return _unpickle_quantity, (Quantity, self.magnitude, self._units)
-
     def __dask_tokenize__(self):
         return uuid.uuid4().hex
 
@@ -88,11 +59,6 @@ def to_openmm(self) -> "OpenMMQuantity":
 class Measurement(_Measurement):
     """A value with associated units and uncertainty."""
 
-    _REGISTRY = DEFAULT_UNIT_REGISTRY
-
-    def __reduce__(self):
-        return _unpickle_measurement, (Measurement, self.magnitude, self._units)
-
     def __dask_tokenize__(self):
         return uuid.uuid4().hex
 
@@ -102,9 +68,17 @@ def _dask_finalize(results, func, args, units):
         return Measurement(values, units)
 
 
-DEFAULT_UNIT_REGISTRY.Unit = Unit
-DEFAULT_UNIT_REGISTRY.Quantity = Quantity
-DEFAULT_UNIT_REGISTRY.Measurement = Measurement
+class UnitRegistry(_UnitRegistry):
+    _quantity_class = Quantity
+    _unit_class = Unit
+    _measurement_class = Measurement
+
+
+DEFAULT_UNIT_REGISTRY = UnitRegistry(get_defaults_path())
+
+Unit: _Unit = DEFAULT_UNIT_REGISTRY.Unit  # type: ignore[no-redef]
+Quantity: _Quantity = DEFAULT_UNIT_REGISTRY.Quantity  # type: ignore[no-redef]
+Measurement: _Measurement = DEFAULT_UNIT_REGISTRY.Measurement  # type: ignore[no-redef]
 
 pint.set_application_registry(DEFAULT_UNIT_REGISTRY)
 
diff --git a/setup.cfg b/setup.cfg
index 43ef0a5..1d15025 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -16,6 +16,8 @@ exclude_lines =
 [flake8]
 max-line-length = 119
 ignore = E203,W503
+per-file-ignores =
+    openff/units/units.py:F811
 
 [isort]
 multi_line_output=3
@@ -47,14 +49,8 @@ ignore_missing_imports = True
 [mypy-pint.*]
 ignore_missing_imports = True
 
-[mypy-openff.utilities.*]
-ignore_missing_imports = True
-
 [mypy-openmm]
 ignore_missing_imports = True
 
 [mypy-openmm.unit]
 ignore_missing_imports = True
-
-[mypy-openmm.app.element]
-ignore_missing_imports = True