diff --git a/graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_shutdown.py b/graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_shutdown.py
index 9270af5914..68855dfe2e 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_shutdown.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_shutdown.py
@@ -47,7 +47,6 @@
 import sys
 from unittest import skipIf
 from tests import compile_module_from_string
-from tests.util import skip_if_sandboxed
 
 GRAALPY = sys.implementation.name == 'graalpy'
 
@@ -77,7 +76,6 @@ def test_sigterm():
     assert proc.wait() in [-signal.SIGTERM, 128 + signal.SIGTERM]
 
 
-@skip_if_sandboxed("Needs native extension support in sandboxed runs")
 @skipIf(not GRAALPY, "GraalPy-only native weakref shutdown test")
 def test_native_weakref_shutdown_skips_c_retained_object():
     module = compile_module_from_string(textwrap.dedent("""
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/standalone/test_standalone.py b/graalpython/com.oracle.graal.python.test/src/tests/standalone/test_standalone.py
index 6b51f714dd..1ed2b27f52 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/standalone/test_standalone.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/standalone/test_standalone.py
@@ -1,4 +1,4 @@
-# Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2023, 2026, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # The Universal Permissive License (UPL), Version 1.0
@@ -38,6 +38,7 @@
 # SOFTWARE.
 
 import os
+import sys
 import tempfile
 import unittest
 
@@ -69,6 +70,9 @@ def create_test_env():
     env["PIP_CONSTRAINT"] = constraints_file
     return env
 
+def append_env_flag(env, key, flag):
+    env[key] = (env.get(key, "") + " " + flag).strip()
+
 @unittest.skipUnless(is_enabled, "ENABLE_STANDALONE_UNITTESTS is not true")
 def test_native_executable_one_file():
     graalpy = util.get_gp()
@@ -124,7 +128,10 @@ def test_native_executable_venv_and_one_file():
 
         venv_python = os.path.join(venv_dir, "Scripts", "python.exe") if os.name == "nt" else os.path.join(venv_dir, "bin", "python")
         cmd = [venv_python, "-m", "pip", "install", "termcolor", "ujson"]
-        _, return_code = util.run_cmd(cmd, env, logger=log)
+        pip_env = env.copy()
+        if sys.platform == "darwin":
+            append_env_flag(pip_env, "CXXFLAGS", "-std=c++11")
+        _, return_code = util.run_cmd(cmd, pip_env, logger=log)
         assert return_code == 0, log
 
         target_file = os.path.join(target_dir, "hello")
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/test_call-classmethod.py b/graalpython/com.oracle.graal.python.test/src/tests/test_call-classmethod.py
index 2bf5e689eb..633b298375 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/test_call-classmethod.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/test_call-classmethod.py
@@ -23,6 +23,9 @@
 # OF THE POSSIBILITY OF SUCH DAMAGE.
 # classmethod calls
 
+from tests.util import needs_capi
+
+
 class Strength(object):
 
     def __init__(self, strength, name):
@@ -171,6 +174,7 @@ class Child(Parent):
     assert Parent.__subclasses__() == []
 
 
+@needs_capi
 def test_cext_classmethod_descriptor():
     from _ctypes import _SimpleCData
 
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/test_ctypes.py b/graalpython/com.oracle.graal.python.test/src/tests/test_ctypes.py
index ff44710f02..d81c6446dc 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/test_ctypes.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/test_ctypes.py
@@ -46,7 +46,6 @@
 from pathlib import Path
 
 from tests.testlib_helper import build_testlib
-from tests.util import skip_if_sandboxed
 
 
 class TestCtypesInterop(unittest.TestCase):
@@ -75,7 +74,6 @@ def run_in_subprocess(self, code, *args):
                 )
             )
 
-    @skip_if_sandboxed("Needs native extension support for ctypes in sandboxed runs")
     def test_ctypes_load_and_call(self):
         # Pass the library path as an argument
         code = textwrap.dedent(
@@ -93,7 +91,6 @@ def test_ctypes_load_and_call(self):
         self.run_in_subprocess(code, str(self.lib_path))
 
     @unittest.skipIf(sys.platform != "win32", "Windows-only test")
-    @skip_if_sandboxed("Needs native extension support for ctypes in sandboxed runs")
     def test_os_add_dll_directory_and_unload(self):
         # Pass the library dir as argument
         code = textwrap.dedent(
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/test_entropy_subprocess.py b/graalpython/com.oracle.graal.python.test/src/tests/test_entropy_subprocess.py
index 9432922a45..0016e3b083 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/test_entropy_subprocess.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/test_entropy_subprocess.py
@@ -45,7 +45,7 @@
 import threading
 import unittest
 
-from tests.util import skip_if_sandboxed
+from tests.util import needs_capi
 
 
 @unittest.skipUnless(sys.implementation.name == "graalpy" and sys.platform.startswith("linux"), "Linux GraalPy-specific test")
@@ -279,7 +279,7 @@ def test_pyexpat_parsercreate_does_not_use_additional_initrandom(self):
             "xmlparser",
         )
 
-    @skip_if_sandboxed("Needs native extension support for sqlite3 in sandboxed runs")
+    @needs_capi
     def test_sqlite3_import_does_not_use_additional_initrandom(self):
         self.assert_initrandom_bytes_used(
             self.HASH_SECRET_BYTES,
@@ -287,7 +287,7 @@ def test_sqlite3_import_does_not_use_additional_initrandom(self):
             "_sqlite3",
         )
 
-    @skip_if_sandboxed("Needs native extension support for sqlite3 in sandboxed runs")
+    @needs_capi
     def test_sqlite3_randomblob_does_not_use_initrandom(self):
         self.assert_initrandom_bytes_used(
             self.HASH_SECRET_BYTES,
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/test_indirect_call.py b/graalpython/com.oracle.graal.python.test/src/tests/test_indirect_call.py
index b0ae60ae95..052067ec3d 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/test_indirect_call.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/test_indirect_call.py
@@ -40,6 +40,7 @@
 import os
 
 from tests.cpyext import CPyExtTestCase, CPyExtType
+from tests.util import has_capi, needs_capi
 
 # synchronize with Java implementation of __graalpython__.indirect_call_tester
 TYPE_INDIRECT_BOUNDARY = 1
@@ -70,15 +71,18 @@ def was_stack_walk(new_value):
     return False
 
 
-IndirectCApiCallTester = CPyExtType(
-    'IndirectCApiCallTester',
-    code='''
-    static PyObject* IndirectCApiCallTester_call(PyObject* self, PyObject *callable) {
-        return PyObject_CallNoArgs(callable);
-    }
-    ''',
-    tp_methods='''{"call", (PyCFunction)IndirectCApiCallTester_call, METH_O, ""}''',
-)
+if has_capi():
+    IndirectCApiCallTester = CPyExtType(
+        'IndirectCApiCallTester',
+        code='''
+        static PyObject* IndirectCApiCallTester_call(PyObject* self, PyObject *callable) {
+            return PyObject_CallNoArgs(callable);
+        }
+        ''',
+        tp_methods='''{"call", (PyCFunction)IndirectCApiCallTester_call, METH_O, ""}''',
+    )
+else:
+    IndirectCApiCallTester = None
 
 # === capturing frame
 
@@ -96,6 +100,7 @@ def fun(x):
         stack_walks += was_stack_walk(False)
     assert stack_walks <= ALLOWED_NUM_STACK_WALKS, f"Too many stack walks recorded: {stack_walks}"
 
+@needs_capi
 def test_capi_get_frame():
     check_get_frame_no_deopt(IndirectCApiCallTester().call)
 
@@ -174,6 +179,7 @@ def check_ex(msg):
         stack_walks += was_stack_walk(False)
     assert stack_walks <= ALLOWED_NUM_STACK_WALKS, f"Too many stack walks recorded: {stack_walks}"
 
+@needs_capi
 def test_capi_get_ex():
     check_get_ex_no_deopt(IndirectCApiCallTester().call)
 
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/test_sqlite3.py b/graalpython/com.oracle.graal.python.test/src/tests/test_sqlite3.py
index 21ae70d3bb..c4614bce56 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/test_sqlite3.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/test_sqlite3.py
@@ -37,10 +37,10 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-from tests.util import skip_if_sandboxed
+from tests.util import needs_capi
 
 
-@skip_if_sandboxed("Needs native extension support for sqlite3 in sandboxed runs")
+@needs_capi
 def test_basic_functionality():
     """
     This is a basic test to ensure that the module can be imported.
@@ -55,7 +55,7 @@ def test_basic_functionality():
     conn.close()
 
 
-@skip_if_sandboxed("Needs native extension support for sqlite3 in sandboxed runs")
+@needs_capi
 def test_fts5_works():
     # we explicitly enable those features below, but on CPython they might not
     # be available if using some system libsqlite that doesn't have them
diff --git a/graalpython/com.oracle.graal.python.test/src/tests/util.py b/graalpython/com.oracle.graal.python.test/src/tests/util.py
index f47e5efbcb..2a3824fb21 100644
--- a/graalpython/com.oracle.graal.python.test/src/tests/util.py
+++ b/graalpython/com.oracle.graal.python.test/src/tests/util.py
@@ -59,6 +59,21 @@ def wrapper(test):
     return wrapper
 
 
+def _jdk_major_version():
+    version = __graalpython__.get_jdk_version()
+    return int(version.split(".", 1)[0].split("-", 1)[0])
+
+
+def has_capi():
+    return not (sys.implementation.name == 'graalpy' and _jdk_major_version() < 25)
+
+
+def needs_capi(test):
+    if not has_capi():
+        return unittest.skip("Needs C API support on JDK 25 or newer")(test)
+    return test
+
+
 def skipIfBytecodeDSL(reason=''):
     def wrapper(test):
         if IS_BYTECODE_DSL:
diff --git a/graalpython/lib-python/3/test/_test_multiprocessing.py b/graalpython/lib-python/3/test/_test_multiprocessing.py
index 2903cb25b5..625454b371 100644
--- a/graalpython/lib-python/3/test/_test_multiprocessing.py
+++ b/graalpython/lib-python/3/test/_test_multiprocessing.py
@@ -3221,7 +3221,8 @@ def test_mymanager(self):
         # bpo-30356: BaseManager._finalize_manager() sends SIGTERM
         # to the manager process if it takes longer than 1 second to stop,
         # which happens on slow buildbots.
-        self.assertIn(manager._process.exitcode, (0, -signal.SIGTERM))
+        # GraalPy change: JVM exits with 143 on SIGTERM
+        self.assertIn(manager._process.exitcode, (0, -signal.SIGTERM, 128 + signal.SIGTERM))
 
     def test_mymanager_context(self):
         manager = MyManager(shutdown_timeout=SHUTDOWN_TIMEOUT)
@@ -3230,7 +3231,8 @@ def test_mymanager_context(self):
         # bpo-30356: BaseManager._finalize_manager() sends SIGTERM
         # to the manager process if it takes longer than 1 second to stop,
         # which happens on slow buildbots.
-        self.assertIn(manager._process.exitcode, (0, -signal.SIGTERM))
+        # GraalPy change: JVM exits with 143 on SIGTERM
+        self.assertIn(manager._process.exitcode, (0, -signal.SIGTERM, 128 + signal.SIGTERM))
 
     def test_mymanager_context_prestarted(self):
         manager = MyManager(shutdown_timeout=SHUTDOWN_TIMEOUT)
diff --git a/mx.graalpython/mx_graalpython.py b/mx.graalpython/mx_graalpython.py
index 8392bc9d86..d7d862f354 100644
--- a/mx.graalpython/mx_graalpython.py
+++ b/mx.graalpython/mx_graalpython.py
@@ -1399,8 +1399,8 @@ def run_sandboxed_tests(python_binary, report, args=None, **kwargs):
         # C API doesn't work on JDK 21
         exclude += [
             "cpyext",
+            "test_ctypes",
             "test_ctypes_callbacks",
-            "test_indirect_call",
         ]
     env = dict(kwargs.pop("env", os.environ.copy()) or {})
     propagated_args = [