diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 7cb89940..74fefe20 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -15,7 +15,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: [3.9]
+        python-version: [3.11]
 
     runs-on: ${{ matrix.os }}
     defaults:
@@ -23,9 +23,9 @@ jobs:
         shell: bash -l {0}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}
-        uses: conda-incubator/setup-miniconda@v2
+        uses: conda-incubator/setup-miniconda@v3
         with:
           auto-update-conda: true
           python-version: ${{ matrix.python-version }}
@@ -39,7 +39,8 @@ jobs:
       - name: Install dependencies
         run: |
           conda info
-          conda install -c conda-forge numpy cython h5py
+          conda install -c conda-forge numpy 'cython<3.0' h5py
+          python -m pip install --upgrade pip setuptools wheel
           python -m pip install https://github.com/pypr/cyarray/zipball/master
           python -m pip install https://github.com/pypr/compyle/zipball/master
           python -m pip install -r requirements.txt -r requirements-test.txt
diff --git a/.github/workflows/zoltan-tests.yml b/.github/workflows/zoltan-tests.yml
index 105a88db..c947706a 100644
--- a/.github/workflows/zoltan-tests.yml
+++ b/.github/workflows/zoltan-tests.yml
@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python-version: [3.9]
+        python-version: [3.11]
 
     env:
       USE_TRILINOS: 1
@@ -26,13 +26,13 @@ jobs:
         shell: bash -l {0}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Linux packages ZOLTAN support
         run: |
           sudo apt-get update
           sudo apt-get install -y openmpi-bin libopenmpi-dev libtrilinos-zoltan-dev
       - name: Set up Python ${{ matrix.python-version }}
-        uses: conda-incubator/setup-miniconda@v2
+        uses: conda-incubator/setup-miniconda@v3
         with:
           auto-update-conda: true
           python-version: ${{ matrix.python-version }}
@@ -40,8 +40,10 @@ jobs:
       - name: Install dependencies
         run: |
           conda info
-          conda install -c conda-forge numpy cython
-          python -m pip install mpi4py cyarray
+          conda install -c conda-forge numpy 'cython<3.0'
+          python -m pip install --upgrade pip setuptools wheel
+          python -m pip install mpi4py
+          python -m pip install https://github.com/pypr/cyarray/zipball/master
           python -m pip install --no-build-isolation https://github.com/pypr/pyzoltan/zipball/master
           python -m pip install https://github.com/pypr/compyle/zipball/master
           python -m pip install -r requirements.txt
diff --git a/pyproject.toml b/pyproject.toml
index ece6eb95..5aa017ac 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [build-system]
 requires = [
     "Beaker",
-    "Cython>=0.20",
+    "Cython<3.0",
     "compyle>=0.8",
     "cyarray",
     "mako",
diff --git a/pysph/base/linalg3.pyx b/pysph/base/linalg3.pyx
index 1130654f..5c4391f3 100644
--- a/pysph/base/linalg3.pyx
+++ b/pysph/base/linalg3.pyx
@@ -11,7 +11,7 @@ from numpy.linalg import eigh
 cimport numpy
 import numpy
 
-cdef extern:
+cdef extern from "math.h":
     double fabs(double) nogil
 
 # this is cython substitute for const values
diff --git a/pysph/base/nnps_base.pyx b/pysph/base/nnps_base.pyx
index dfa35701..0e147e90 100644
--- a/pysph/base/nnps_base.pyx
+++ b/pysph/base/nnps_base.pyx
@@ -47,13 +47,6 @@ ELSE:
     cpdef set_number_of_threads(int n):
         print("OpenMP not available, cannot set number of threads.")
 
-
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
 # Particle Tag information
 from cyarray.carray cimport BaseArray, aligned_malloc, aligned_free
 from .utils import ParticleTAGS
diff --git a/pysph/base/octree.pyx b/pysph/base/octree.pyx
index 5f46bc2c..5960a49f 100644
--- a/pysph/base/octree.pyx
+++ b/pysph/base/octree.pyx
@@ -15,12 +15,6 @@ from cython.parallel import parallel, prange, threadid
 # EPS_MAX is maximum value of eps in tree building
 DEF EPS_MAX = 1e-3
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
 ctypedef cOctreeNode* node_ptr
 ctypedef double* dbl_ptr
 
diff --git a/pysph/base/octree_nnps.pyx b/pysph/base/octree_nnps.pyx
index 4bbba26a..14c98a99 100644
--- a/pysph/base/octree_nnps.pyx
+++ b/pysph/base/octree_nnps.pyx
@@ -9,13 +9,6 @@ from libc.stdlib cimport malloc, free
 cimport cython
 from cython.operator cimport dereference as deref, preincrement as inc
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
-
 #############################################################################
 cdef class OctreeNNPS(NNPS):
     """Nearest neighbor search using Octree.
diff --git a/pysph/base/spatial_hash_nnps.pyx b/pysph/base/spatial_hash_nnps.pyx
index 65a0b4c6..9878dda3 100644
--- a/pysph/base/spatial_hash_nnps.pyx
+++ b/pysph/base/spatial_hash_nnps.pyx
@@ -8,13 +8,6 @@ from libcpp.vector cimport vector
 # Cython for compiler directives
 cimport cython
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
-
 #############################################################################
 cdef class SpatialHashNNPS(NNPS):
 
diff --git a/pysph/base/stratified_hash_nnps.pyx b/pysph/base/stratified_hash_nnps.pyx
index 29ac4b3f..72bf6691 100644
--- a/pysph/base/stratified_hash_nnps.pyx
+++ b/pysph/base/stratified_hash_nnps.pyx
@@ -12,12 +12,6 @@ cimport cython
 
 DEF EPS = 1e-6
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
 #############################################################################
 cdef class StratifiedHashNNPS(NNPS):
 
diff --git a/pysph/base/stratified_sfc_gpu_nnps.pyx b/pysph/base/stratified_sfc_gpu_nnps.pyx
index a6ee0349..413cf177 100644
--- a/pysph/base/stratified_sfc_gpu_nnps.pyx
+++ b/pysph/base/stratified_sfc_gpu_nnps.pyx
@@ -38,13 +38,6 @@ cdef extern from *:
     #endif
     """
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
-
 cdef class StratifiedSFCGPUNNPS(GPUNNPS):
     def __init__(self, int dim, list particles, double radius_scale=2.0,
             int ghost_layers=1, domain=None, bint fixed_h=False,
diff --git a/pysph/base/stratified_sfc_nnps.pyx b/pysph/base/stratified_sfc_nnps.pyx
index 0f27e3c4..63b44f0d 100644
--- a/pysph/base/stratified_sfc_nnps.pyx
+++ b/pysph/base/stratified_sfc_nnps.pyx
@@ -33,13 +33,6 @@ cdef extern from *:
     #endif
     """
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
-
 #############################################################################
 cdef class StratifiedSFCNNPS(NNPS):
 
diff --git a/pysph/base/z_order_gpu_nnps.pyx b/pysph/base/z_order_gpu_nnps.pyx
index 3807d7e9..5a2ec5c8 100644
--- a/pysph/base/z_order_gpu_nnps.pyx
+++ b/pysph/base/z_order_gpu_nnps.pyx
@@ -44,13 +44,6 @@ cdef extern from *:
     #endif
     """
 
-IF UNAME_SYSNAME == "Windows":
-    cdef inline double fmin(double x, double y) nogil:
-        return x if x < y else y
-    cdef inline double fmax(double x, double y) nogil:
-        return x if x > y else y
-
-
 cdef class ZOrderGPUNNPS(GPUNNPS):
     def __init__(self, int dim, list particles, double radius_scale=2.0,
             int ghost_layers=1, domain=None, bint fixed_h=False,
diff --git a/requirements.txt b/requirements.txt
index ccb71adf..5426b1f9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 numpy
 setuptools>=42.0.0
-Cython>=0.20
+Cython<3.0
 cyarray
 compyle>=0.8
 mako
diff --git a/setup.py b/setup.py
index 9c528fc4..ae13fc67 100644
--- a/setup.py
+++ b/setup.py
@@ -681,7 +681,7 @@ def setup_package():
 
     # The requirements.
     install_requires = [
-        'numpy', 'mako', 'cyarray', 'compyle>=0.8', 'Cython>=0.20',
+        'numpy', 'mako', 'cyarray', 'compyle>=0.8', 'Cython<3.0',
         'setuptools>=42.0.0', 'pytools', 'Beaker'
     ]
     tests_require = ['pytest>=3.0', 'h5py', 'vtk']