diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 03a8c41..f59842f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -38,7 +38,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [macos-latest, windows-latest, ubuntu-latest]
-        python-version: ["3.10", "3.11", "3.12-dev"]
+        python-version: ["3.10", "3.11", "3.12", "pypy3.10"]
 
     runs-on: ${{ matrix.os }}
     name: ${{ fromJson('{"macos-latest":"macOS","windows-latest":"Windows","ubuntu-latest":"Ubuntu"}')[matrix.os] }} Python ${{ matrix.python-version }}
@@ -49,9 +49,10 @@ jobs:
         uses: actions/checkout@v3
 
       - name: Setup Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v3
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
+          allow-prereleases: true
 
       - name: Setup Go
         uses: actions/setup-go@v3
diff --git a/src/truststore/_api.py b/src/truststore/_api.py
index 571ea3c..3c28065 100644
--- a/src/truststore/_api.py
+++ b/src/truststore/_api.py
@@ -6,7 +6,12 @@
 
 import _ssl  # type: ignore[import]
 
-from ._ssl_constants import _original_SSLContext, _original_super_SSLContext
+from ._ssl_constants import (
+    _original_SSLContext,
+    _original_super_SSLContext,
+    _truststore_SSLContext_dunder_class,
+    _truststore_SSLContext_super_class,
+)
 
 if platform.system() == "Windows":
     from ._windows import _configure_context, _verify_peercerts_impl
@@ -49,9 +54,16 @@ def extract_from_ssl() -> None:
         pass
 
 
-class SSLContext(ssl.SSLContext):
+class SSLContext(_truststore_SSLContext_super_class):  # type: ignore[misc]
     """SSLContext API that uses system certificates on all platforms"""
 
+    @property  # type: ignore[misc]
+    def __class__(self) -> type:
+        # Dirty hack to get around isinstance() checks
+        # for ssl.SSLContext instances in aiohttp/trustme
+        # when using non-CPython implementations.
+        return _truststore_SSLContext_dunder_class or SSLContext
+
     def __init__(self, protocol: int = None) -> None:  # type: ignore[assignment]
         self._ctx = _original_SSLContext(protocol)
 
@@ -240,7 +252,7 @@ def protocol(self) -> ssl._SSLMethod:
         return self._ctx.protocol
 
     @property
-    def security_level(self) -> int:  # type: ignore[override]
+    def security_level(self) -> int:
         return self._ctx.security_level
 
     @property
diff --git a/src/truststore/_ssl_constants.py b/src/truststore/_ssl_constants.py
index be60f83..b1ee7a3 100644
--- a/src/truststore/_ssl_constants.py
+++ b/src/truststore/_ssl_constants.py
@@ -1,10 +1,29 @@
 import ssl
+import sys
+import typing
 
 # Hold on to the original class so we can create it consistently
 # even if we inject our own SSLContext into the ssl module.
 _original_SSLContext = ssl.SSLContext
 _original_super_SSLContext = super(_original_SSLContext, _original_SSLContext)
 
+# CPython is known to be good, but non-CPython implementations
+# may implement SSLContext differently so to be safe we don't
+# subclass the SSLContext.
+
+# This is returned by truststore.SSLContext.__class__()
+_truststore_SSLContext_dunder_class: typing.Optional[type]
+
+# This value is the superclass of truststore.SSLContext.
+_truststore_SSLContext_super_class: type
+
+if sys.implementation.name == "cpython":
+    _truststore_SSLContext_super_class = _original_SSLContext
+    _truststore_SSLContext_dunder_class = None
+else:
+    _truststore_SSLContext_super_class = object
+    _truststore_SSLContext_dunder_class = _original_SSLContext
+
 
 def _set_ssl_context_verify_mode(
     ssl_context: ssl.SSLContext, verify_mode: ssl.VerifyMode