diff --git a/.github/workflows/cov.yml b/.github/workflows/cov.yml
index 3587ad81..35c44e5d 100644
--- a/.github/workflows/cov.yml
+++ b/.github/workflows/cov.yml
@@ -16,7 +16,7 @@ env:
 
 jobs:
   cov:
-    runs-on: macos-10.15
+    runs-on: macos-11
     steps:
     - uses: actions/checkout@v2
     - name: Fetch Boost superproject