diff --git a/.github/workflows/phpunit.yml b/.github/workflows/phpunit.yml
index 0fe5be863dc1..101e4a3759dd 100644
--- a/.github/workflows/phpunit.yml
+++ b/.github/workflows/phpunit.yml
@@ -12,8 +12,8 @@ jobs:
     runs-on: ${{ matrix.operating-system }}
     strategy:
       matrix:
-        operating-system: ['ubuntu-latest']
-        php-versions: ['7.3', '7.4', '8.0']
+        operating-system: ['ubuntu-18.04', 'ubuntu-20.04']
+        php-versions: ['7.3', '7.4', '8.0', '8.1']
         phpunit-versions: ['latest']
         include:
         - operating-system: 'ubuntu-latest'