diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 50cf3c879..4d8dcee4f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -84,7 +84,7 @@ jobs:
 
   build-matrix:
     name: Unit tests - Python versions
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         python-version: [3.8, 3.9, '3.10', '3.11']