diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1536621c..18b08be3 100755
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -12,10 +12,10 @@ jobs:
     - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with:
-        python-version: '3.11.x'
+        python-version: '3.9.x'
     - name: Setup Python
       run: |
-        python3 -m pip install Cython numpy scipy==1.12.0 matplotlib nose-py3
+        python3 -m pip install Cython numpy scipy==1.12.0 matplotlib nose-py3 setuptools==69.1.0
     - name: Install system
       run: |
         sudo apt-get -y install cmake liblapack-dev libsuitesparse-dev libhypre-dev
@@ -40,7 +40,7 @@ jobs:
         sudo make install
     - name: Install assimulo
       run: |
-        git clone --depth 1 -b dev-pm-python_upgrade https://github.com/modelon-community/Assimulo /tmp/Assimulo
+        git clone --depth 1 -b dev-pm-cy3_only https://github.com/modelon-community/Assimulo /tmp/Assimulo
         cd /tmp/Assimulo
         python3 setup.py install --user --sundials-home=/usr --blas-home=/usr/lib/x86_64-linux-gnu/ --lapack-home=/usr/lib/x86_64-linux-gnu/ --superlu-home=/usr --extra-fortran-compile-flags="-fallow-argument-mismatch"
     - name: Install fmilib
diff --git a/setup.cfg b/setup.cfg
index e9aeb933..889cf472 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,12 +1,12 @@
 [options]
 setup_requires =
     setuptools
-    numpy >= 1.26.3
+    numpy >= 1.19.5
     cython >= 3.0
 
 install_requires =
-    numpy >= 1.26.3
-    scipy >= 1.11.4, < 1.13
+    numpy >= 1.19.5
+    scipy >= 1.10.1, < 1.13
     cython >= 3.0.7
     nose-py3 >= 1.6.3
     matplotlib > 3