diff --git a/README.rst b/README.rst
index 64b68f9..46b1acf 100644
--- a/README.rst
+++ b/README.rst
@@ -48,6 +48,8 @@ Requirements:
   or install from source.
 - Python >= 3.9
 - pip
+- `cysignals <https://pypi.python.org/pypi/cysignals/>`_ >= 1.7
+- Cython >= 3.0
 
 Install cypari2 via the Python Package Index (PyPI) via
 
diff --git a/cypari2/closure.pyx b/cypari2/closure.pyx
index 44615fe..42c370e 100644
--- a/cypari2/closure.pyx
+++ b/cypari2/closure.pyx
@@ -31,8 +31,6 @@ Examples:
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
-from __future__ import absolute_import, division, print_function
-
 from cysignals.signals cimport sig_on, sig_off, sig_block, sig_unblock, sig_error
 
 from cpython.tuple cimport *
diff --git a/cypari2/convert.pyx b/cypari2/convert.pyx
index 667f922..c8f93cf 100644
--- a/cypari2/convert.pyx
+++ b/cypari2/convert.pyx
@@ -39,8 +39,6 @@ some bit shuffling.
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
-from __future__ import absolute_import, division, print_function
-
 from cysignals.signals cimport sig_on, sig_off, sig_error
 
 from cpython.version cimport PY_MAJOR_VERSION
diff --git a/cypari2/gen.pxd b/cypari2/gen.pxd
index 0d51866..9579dee 100644
--- a/cypari2/gen.pxd
+++ b/cypari2/gen.pxd
@@ -1,3 +1,4 @@
+cimport cython
 from cpython.object cimport PyObject
 from .types cimport GEN, pari_sp
 
diff --git a/cypari2/gen.pyx b/cypari2/gen.pyx
index 60a4b4f..a109244 100644
--- a/cypari2/gen.pyx
+++ b/cypari2/gen.pyx
@@ -55,8 +55,6 @@ AUTHORS:
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
-from __future__ import absolute_import, division, print_function
-
 cimport cython
 
 from cpython.object cimport (Py_EQ, Py_NE, Py_LE, Py_GE, Py_LT, PyTypeObject)
@@ -143,6 +141,7 @@ cdef extern from *:
     GEN old_nfbasis(GEN x, GEN * y, GEN p)
 
 
+@cython.trashcan(True)
 cdef class Gen(Gen_base):
     """
     Wrapper for a PARI ``GEN`` with memory management.
diff --git a/cypari2/handle_error.pyx b/cypari2/handle_error.pyx
index f32664b..5789ee2 100644
--- a/cypari2/handle_error.pyx
+++ b/cypari2/handle_error.pyx
@@ -21,7 +21,7 @@ AUTHORS:
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
-from __future__ import absolute_import, division, print_function
+from cpython cimport PyErr_Occurred
 
 from cysignals.signals cimport sig_block, sig_unblock, sig_error
 
diff --git a/cypari2/pari_instance.pyx b/cypari2/pari_instance.pyx
index 9a57fbc..65d705a 100644
--- a/cypari2/pari_instance.pyx
+++ b/cypari2/pari_instance.pyx
@@ -243,6 +243,15 @@ Reset default precision for the following tests:
 
 >>> pari.set_real_precision_bits(53)
 
+Test the trashcan mechanism (without the trashcan, this would cause
+a stack overflow):
+
+>>> pari.allocatemem(2**27, silent=True)
+>>> L = [pari(i) for i in range(2**20)]
+>>> x = pari.Pi()
+>>> del L
+>>> del x
+
 Test that interrupts work properly:
 
 >>> pari.allocatemem(8000000, 2**29)
@@ -275,8 +284,6 @@ Test that changing the stack size using ``default`` works properly:
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
-from __future__ import absolute_import, division
-
 import sys
 from libc.stdio cimport *
 cimport cython
diff --git a/cypari2/stack.pyx b/cypari2/stack.pyx
index 04ffcca..b4d51fe 100644
--- a/cypari2/stack.pyx
+++ b/cypari2/stack.pyx
@@ -14,7 +14,6 @@ Memory management for Gens on the PARI stack or the heap
 #                  http://www.gnu.org/licenses/
 # ****************************************************************************
 
-from __future__ import absolute_import, division, print_function
 cimport cython
 
 from cpython.ref cimport PyObject
diff --git a/pyproject.toml b/pyproject.toml
index ff82406..a2c5735 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [build-system]
 requires = ["setuptools",
-            "Cython>=0.29",
+            "Cython>=3.0",
             "cysignals>=1.7"]
 # We need access to the autogen package at build time.
 # Hence we declare a custom build backend.
diff --git a/setup.py b/setup.py
index 51f4c95..c1775b5 100755
--- a/setup.py
+++ b/setup.py
@@ -35,9 +35,9 @@ def finalize_options(self):
             "autotestdict.cdef": True,
             "binding": True,
             "cdivision": True,
-            "language_level": 2,
             "legacy_implicit_noexcept": True,
             "c_api_binop_methods": True,
+            "language_level": "3str",
         }
 
         _build_ext.finalize_options(self)