diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a9de41c0..3ff072ca 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -15,7 +15,7 @@ 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 matplotlib nose-py3
diff --git a/setup.cfg b/setup.cfg
index 935d6c9d..fb40f567 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,13 +1,13 @@
 [options]
 setup_requires =
     setuptools
-    numpy >= 1.26.3
+    numpy >= 1.19.5
     cython >= 3.0.7
 
 install_requires =
-    python >= 3.11
-    numpy >= 1.26.3
-    scipy >= 1.11.4
+    python >= 3.9
+    numpy >= 1.19.5
+    scipy >= 1.10.1
     cython >= 3.0.7
     nose-py3 >= 1.6.3
     matplotlib > 3