diff --git a/.github/workflows/mac.yml b/.github/workflows/mac.yml
index 88660de82a1eeed5279ec860587566d08c255f5f..c0f1754db50de89e96c2410fd6fd60d30c475fa4 100644
--- a/.github/workflows/mac.yml
+++ b/.github/workflows/mac.yml
@@ -4,7 +4,7 @@ on: [push, pull_request]
 
 jobs:
   macOS:
-    runs-on: macos-latest
+    runs-on: macos-10.05
     strategy:
       matrix:
         LCG: ["LCG_98python3/x86_64-mac1015-clang110-opt",