diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index fcb42b9..255b4cf 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -46,7 +46,7 @@ jobs:
   #####################################
   # MacOS with CMake/clang and sign/notarize in self-written script
   build-mac:
-    runs-on: macos-11
+    runs-on: macos-12
     steps:
     - name: Checkout Code
       uses: actions/checkout@v4       # must checkout before we can use our own actions
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 94d90d5..6d8da68 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,6 +22,9 @@ if(DEFINED ENV{platform})
     elseif($ENV{platform} STREQUAL "mac-arm")
         message ("   Building cross-platform for mac/arm64")
         set(CMAKE_OSX_ARCHITECTURES "arm64" CACHE STRING "Archs to build")
+    elseif($ENV{platform} STREQUAL "mac")
+        message ("   Building cross-platform for both mac/x86_64 and mac/arm64")
+        set(CMAKE_OSX_ARCHITECTURES "x86_64;arm64" CACHE STRING "Archs to build")
     endif()
 else()
     # No 'platform' defined could mean running from command line, assume we build universal image in one go via XCode