diff --git a/.github/workflows/python-testing.yml b/.github/workflows/python-testing.yml
index d248cbf7..8336b176 100644
--- a/.github/workflows/python-testing.yml
+++ b/.github/workflows/python-testing.yml
@@ -33,10 +33,13 @@ jobs:
       #  -----  install & configure poetry  -----
       #----------------------------------------------
       - name: Install Poetry
-        uses: snok/install-poetry@v1
+      - uses: snok/install-poetry@v1
         with:
           virtualenvs-create: true
           virtualenvs-in-project: true
+      - run: |
+          poetry config installer.modern-installation false
+      #----------------------------------------------
       #----------------------------------------------
       #       load cached venv if cache exists
       #----------------------------------------------
@@ -93,10 +96,12 @@ jobs:
     #  -----  install & configure poetry  -----
     #----------------------------------------------
     - name: Install Poetry
-      uses: snok/install-poetry@v1
+    - uses: snok/install-poetry@v1
       with:
         virtualenvs-create: true
         virtualenvs-in-project: true
+    - run: |
+        poetry config installer.modern-installation false
     #----------------------------------------------
     #       load cached venv if cache exists
     #----------------------------------------------