diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 2e04685..61d1257 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -10,8 +10,12 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: ['3.6', '3.11']
+        python-version: ['3.11']
         os: [macos-latest, ubuntu-latest, windows-latest]
+        include:
+          # oldest supported python version only available on ubuntu 20.04
+          - python-version: '3.6'
+            os: ubuntu-20.04
       fail-fast: false
 
     steps: