diff --git a/.flake8 b/.flake8
index 998a753..4b8cb1b 100644
--- a/.flake8
+++ b/.flake8
@@ -11,4 +11,4 @@ exclude =
     test-obs*,
     venv
 max-complexity = 10
-
+inline-quotes = "
diff --git a/.github/workflows/CI-build-test.yml b/.github/workflows/CI-build-test.yml
index 6485dd8..b0cdb7a 100644
--- a/.github/workflows/CI-build-test.yml
+++ b/.github/workflows/CI-build-test.yml
@@ -7,13 +7,18 @@ jobs:
   build-and-test:
     name: Build/Test 
     runs-on: ubuntu-20.04
-    steps:    
+    strategy:
+      matrix:
+        python-version:
+          - 3.8.10
+          - 3.11.6
+    steps:
     - uses: actions/checkout@v4
 
-    - name: Use Python
+    - name: Use Python ${{ matrix.python-version }}
       uses: actions/setup-python@v4
       with:
-        python-version: '3.11.6'
+        python-version: ${{ matrix.python-version }}
         cache: 'pip'
 
     - name: Install dependencies
diff --git a/requirements-test.txt b/requirements-test.txt
index e439c39..cc92d30 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,4 +1,4 @@
-coverage
-pytest
-pytest-cov
-pytest-mock
+coverage==7.4.4
+pytest==8.1.1
+pytest-cov==4.1.0
+pytest-mock==3.12.0
diff --git a/requirements.txt b/requirements.txt
index 6de8913..8992f7e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,24 +1,33 @@
-flake8
-Flask
-Flask-WTF
-h3
-h3pandas
-itsdangerous
-jinja2
-keras
-matplotlib
-numpy
-pandas
-Pillow
-prison
-python-magic
-pyyaml
-scikit_learn
-scipy
-six
-tensorflow
-tifffile
-umap_learn
-uWSGI
-werkzeug
-WTForms
+flake8==7.0.0
+flake8-quotes==3.4.0
+Flask==3.0.2
+Flask-WTF==1.2.1
+h3==3.7.7
+h3pandas==0.2.6
+itsdangerous==2.1.2
+Jinja2==3.1.3
+keras==2.14.0;python_version>="3.11"
+keras==2.12.0;python_version=="3.8"
+matplotlib==3.8.3;python_version>="3.11"
+matplotlib==3.7.5;python_version=="3.8"
+numpy==1.26.4;python_version>="3.11"
+numpy==1.23.5;python_version=="3.8"
+pandas==2.1.2;python_version>="3.11"
+pandas==2.0.3;python_version=="3.8"
+pillow==10.2.0
+prison==0.2.1
+python-magic==0.4.27
+PyYAML==6.0.1
+scikit-learn==1.4.1.post1;python_version>="3.11"
+scikit-learn==1.3.2;python_version=="3.8"
+scipy==1.12.0;python_version>="3.11"
+scipy==1.10.1;python_version=="3.8"
+six==1.16.0
+tensorflow==2.14.0;python_version>="3.11"
+tensorflow==2.12.0;python_version=="3.8"
+tifffile==2024.2.12;python_version>="3.11"
+tifffile==2023.7.10;python_version=="3.8"
+umap-learn==0.5.5
+uWSGI==2.0.24
+Werkzeug==3.0.1
+WTForms==3.1.2