diff --git a/.circleci/config.yml b/.circleci/config.yml
index 9e5cd8d..abfb41e 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -41,7 +41,10 @@ jobs:
             R_VERSION="<< parameters.r-version >>"
             # Install rig, R Installation Manager (https://github.com/r-lib/rig) to control installed R version
             if [ "$RUNNER_OS" == "macos" ]; then
-              brew install --cask r-lib/rig/rig
+              # Install specific version of rig (0.8.0) directly from GitHub releases
+              curl -L -o /tmp/rig.pkg https://github.com/r-lib/rig/releases/download/v0.8.0/rig-0.8.0-macOS-arm64.pkg
+              ls -lh /tmp/rig.pkg  # Verify file exists and has reasonable size
+              sudo installer -pkg /tmp/rig.pkg -target /
               rig add $R_VERSION
               # on macOS the R package is installed into a MAJOR.MINOR directory
               # the PATCH is ignored (only one patch version supported) the
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index baf9e00..6a3cd35 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -96,7 +96,13 @@ jobs:
         PKG_VERSION=$(Rscript -e "cat(read.dcf('DESCRIPTION', 'Version')[1])")
 
         if [[ "$RUNNER_OS" == "macOS" ]]; then
-          PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_macos-x86_64.tgz"
+          # Detect architecture: arm64 or x86_64
+          ARCH=$(uname -m)
+          if [[ "$ARCH" == "arm64" || "$ARCH" == "aarch64" ]]; then
+            PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_macos-arm64.tgz"
+          else
+            PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_macos-x86_64.tgz"
+          fi
         elif [[ "$RUNNER_OS" == "Linux" ]]; then
           PKG_NAME="SimpleITK_${PKG_VERSION}_R${R_VERSION_SHORT}_linux-x86_64.tar.gz"
         elif [[ "$RUNNER_OS" == "Windows" ]]; then