diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 780074f..8847fa9 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -44,7 +44,7 @@ jobs:
         - ["3.12",  "mypy"]
         - ["3.11",  "z3c.macro"]
         - ["3.11",  "z3c.pt"]
-    runs-on: ${{ matrix.os[1] }}
+    runs-on: ${{ matrix.os }}
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name
     name: ${{ matrix.config[1] }}
     steps: