diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index eedd3536d..4b12c8cf5 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,3 +1,5 @@
+# for github runner images, see: https://github.com/actions/runner-images?tab=readme-ov-file#available-images
+
 name: CI
 
 on:
@@ -11,9 +13,6 @@ on:
 
 env:
   python_bld_ver: 3.9
-  ubuntu_bld: ubuntu-20.04
-  mac_bld: macOS-13
-  windows_bld: windows-2022
   ubuntu_test: ubuntu-latest
   mac_test: macOS-latest
   windows_test: windows-latest
@@ -34,22 +33,22 @@ jobs:
             options: "-debug_64"
             artifact_name: "libebm_ubuntu_debug_64"
           - name: mac_release_64
-            image: macOS-13
+            image: macos-13
             asm: "-asm"
             options: "-release_64"
             artifact_name: "libebm_mac_release_64"
           - name: mac_debug_64
-            image: macOS-13
+            image: macos-13
             asm: ""
             options: "-debug_64"
             artifact_name: "libebm_mac_debug_64"
           - name: mac_release_arm
-            image: macOS-13-arm64
+            image: macos-14
             asm: "-asm"
             options: "-release_arm"
             artifact_name: "libebm_mac_release_arm"
           - name: mac_debug_arm
-            image: macOS-13-arm64
+            image: macos-14
             asm: ""
             options: "-debug_arm"
             artifact_name: "libebm_mac_debug_arm"