diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 4b061d8e..8cd5e1b9 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -26,7 +26,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
 
     - name: Install dependencies
-      run: python -m pip install --upgrade --force-reinstall cython numpy scipy matplotlib corner getdist h5py pandas flake8 pycodestyle pydocstyle pytest-html pytest-xdist
+      run: python -m pip install cython numpy scipy matplotlib corner getdist h5py pandas flake8 pycodestyle pydocstyle pytest-html pytest-xdist
 
     - name: Lint with flake8
       run: flake8 $(ls ultranest/*.py | grep -Ev '^ultranest/(flatnuts|dychmc|dyhmc|pathsampler).py')
diff --git a/setup.py b/setup.py
index 90b619a4..5cb8d449 100644
--- a/setup.py
+++ b/setup.py
@@ -33,7 +33,7 @@
         history_file.read())
     
 
-requirements = ['numpy', 'cython', 'matplotlib', 'corner']
+requirements = ['numpy<2', 'cython', 'matplotlib', 'corner']
 
 setup_requirements = ['pytest-runner', ]