diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index f1f06ab..380e01b 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -5,27 +5,27 @@ on: [push, pull_request]
 jobs:
   build:
 
-    name: "build (${{ matrix.runs_on }}, ${{ matrix.python }})"
+    name: "build (${{ matrix.runs_on }}, ${{ matrix.python }} - Cython ${{ matrix.cython }})"
     runs-on: ${{ matrix.runs_on }}
     strategy:
       matrix:
-        include:
-          - runs_on: macos-latest
-            python: "3.7"
-          - runs_on: macos-latest
-            python: "3.8"
-          - runs_on: macos-latest
-            python: "3.9"
-          - runs_on: macos-latest
-            python: "3.10"
-          - runs_on: macos-latest
-            python: "3.11"
-          - runs_on: apple-silicon-m1
-            python: "3.9"
+        runs_on:
+          - macos-latest
+          - apple-silicon-m1
+        python:
+          - "3.7"
+          - "3.8"
+          - "3.9"
+          - "3.10"
+          - "3.11"
+        cython:
+          - "<3"
+          - ">=3"
+        exclude:
           - runs_on: apple-silicon-m1
-            python: "3.10"
+            python: "3.7"
           - runs_on: apple-silicon-m1
-            python: "3.11"
+            python: "3.8"
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python }}
@@ -35,6 +35,9 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
 
+    - name: Force Cython version
+      run: sed -i.bak 's/"Cython"/"Cython${{matrix.cython}}"/' pyproject.toml
+
     - name: Install project
       run: |
         source .ci/osx_ci.sh
diff --git a/pyobjus/pyobjus.pyx b/pyobjus/pyobjus.pyx
index 4dfda18..b007a96 100644
--- a/pyobjus/pyobjus.pyx
+++ b/pyobjus/pyobjus.pyx
@@ -49,6 +49,11 @@ from libcpp cimport bool
 
 # library files
 include "config.pxi"
+
+# from Cython 3.0, in the MetaJavaClass, this is accessed as _JavaClass__cls_storage
+# see https://cython.readthedocs.io/en/latest/src/userguide/migrating_to_cy30.html#class-private-name-mangling
+cdef CLS_STORAGE_NAME = '_JavaClass__cls_storage' if PYOBJUS_CYTHON_3 else '__cls_storage'
+
 include "debug.pxi"
 include "common.pxi"
 include "type_enc.pxi"
@@ -129,7 +134,7 @@ class MetaObjcClass(type):
             raise ObjcException('Unable to find class {0!r}'.format(
                 __objcclass__))
 
-        classDict['__cls_storage'] = storage
+        classDict[CLS_STORAGE_NAME] = storage
 
         cdef ObjcMethod om
         for name, value in classDict.iteritems():
@@ -431,7 +436,7 @@ cdef class ObjcMethod(object):
             raise MemoryError('Unable to allocate res_ptr')
 
         if not self.signature_return[0].startswith((b'(', b'{')):
-            ffi_call(&self.f_cif, <void(*)()><id(*)(id, SEL)>objc_msgSend, res_ptr, f_args)
+            ffi_call(&self.f_cif, <void(*)() noexcept><id(*)(id, SEL)>objc_msgSend, res_ptr, f_args)
 
         else:
             # TODO FIXME NOTE: Currently this only work on x86_64 architecture and armv7 ios
@@ -460,20 +465,20 @@ cdef class ObjcMethod(object):
                     stret = True
 
                 if stret and MACOS_HAVE_OBJMSGSEND_STRET:
-                    ffi_call(&self.f_cif, <void(*)()><id(*)(id, SEL)>objc_msgSend_stret__safe, res_ptr, f_args)
+                    ffi_call(&self.f_cif, <void(*)() noexcept><id(*)(id, SEL)>objc_msgSend_stret__safe, res_ptr, f_args)
                     fun_name = "objc_msgSend_stret"
                     del_res_ptr = False
                 else:
-                    ffi_call(&self.f_cif, <void(*)()><id(*)(id, SEL)>objc_msgSend, res_ptr, f_args)
+                    ffi_call(&self.f_cif, <void(*)() noexcept><id(*)(id, SEL)>objc_msgSend, res_ptr, f_args)
                     fun_name = "objc_msgSend"
                 dprint("x86_64 architecture {0} call".format(fun_name), of_type='i')
 
             ELIF PLATFORM == 'ios':
                 IF ARCH == 'arm64':
-                    ffi_call(&self.f_cif, <void(*)()><id(*)(id, SEL)>objc_msgSend, res_ptr, f_args)
+                    ffi_call(&self.f_cif, <void(*)() noexcept><id(*)(id, SEL)>objc_msgSend, res_ptr, f_args)
                     dprint('ios(arm64) platform objc_msgSend call')
                 ELSE:
-                    ffi_call(&self.f_cif, <void(*)()><id(*)(id, SEL)>objc_msgSend_stret, res_ptr, f_args)
+                    ffi_call(&self.f_cif, <void(*)() noexcept><id(*)(id, SEL)>objc_msgSend_stret, res_ptr, f_args)
                     dprint('ios(armv7) platform objc_msgSend_stret call')
 
             ELSE:
diff --git a/pyobjus/pyobjus_types.pxi b/pyobjus/pyobjus_types.pxi
index 2345782..34c0b0f 100644
--- a/pyobjus/pyobjus_types.pxi
+++ b/pyobjus/pyobjus_types.pxi
@@ -612,7 +612,7 @@ cdef class ObjcClassInstance:
         super(ObjcClassInstance, self).__init__()
         cdef ObjcClassStorage storage
         if 'getcls' not in kwargs:
-            storage = self.__cls_storage
+            storage = getattr(self, CLS_STORAGE_NAME)
             self.o_cls = storage.o_cls
 
         if 'noinstance' not in kwargs:
diff --git a/setup.py b/setup.py
index 61ae110..d34e39e 100644
--- a/setup.py
+++ b/setup.py
@@ -56,7 +56,10 @@ def build_extensions(self):
         config_pxi_fn = join(dirname(__file__), 'pyobjus', 'config.pxi')
         config_pxi_need_update = True
         config_pxi = 'DEF PLATFORM = "{}"\n'.format(dev_platform)
-        config_pxi += 'DEF ARCH = "{}"'.format(arch)
+        config_pxi += 'DEF ARCH = "{}"\n'.format(arch)
+        import Cython
+        cython3 = Cython.__version__.startswith('3.')
+        config_pxi += f"DEF PYOBJUS_CYTHON_3 = {cython3}"
         if exists(config_pxi_fn):
             with open(config_pxi_fn) as fd:
                 config_pxi_need_update = fd.read() != config_pxi