diff --git a/cache-magento/action.yml b/cache-magento/action.yml
index 5e7f395..fed6235 100644
--- a/cache-magento/action.yml
+++ b/cache-magento/action.yml
@@ -37,6 +37,7 @@ runs:
       run: |
         bash "${{ github.action_path }}/compute-cache-keys.sh" \
           "${{ inputs.composer_cache_key }}" \
+          "${{ runner.os }}" \
           "${{ steps.cache-magento-get-php-version.outputs.version }}" \
           "${{ steps.cache-magento-get-composer-version.outputs.version }}" \
           >> $GITHUB_OUTPUT
diff --git a/cache-magento/compute-cache-keys.sh b/cache-magento/compute-cache-keys.sh
index 38ad49f..9ed78cb 100644
--- a/cache-magento/compute-cache-keys.sh
+++ b/cache-magento/compute-cache-keys.sh
@@ -1,7 +1,8 @@
 #!/usr/bin/env bash
-# Args: composer_cache_key php_version composer_version
+# Args: composer_cache_key os php_version composer_version
 COMPOSER_CACHE_KEY="$1"
-PHP_VERSION="$2"
-COMPOSER_VERSION="$3"
+OS="$2"
+PHP_VERSION="$3"
+COMPOSER_VERSION="$4"
 
-echo "download-key=composer | v5.8 | ${COMPOSER_CACHE_KEY} | ${COMPOSER_VERSION} | ${PHP_VERSION}"
+echo "download-key=composer | v5.8 | ${OS} | ${COMPOSER_CACHE_KEY} | ${COMPOSER_VERSION} | ${PHP_VERSION}"
diff --git a/cache-magento/test.sh b/cache-magento/test.sh
index c8a2e3d..02e7e18 100644
--- a/cache-magento/test.sh
+++ b/cache-magento/test.sh
@@ -22,16 +22,22 @@ field() {
   echo "$1" | grep "^${2}=" | cut -d= -f2-
 }
 
-# Default cache key
-OUT=$(bash "$SCRIPT" "_mageos" "8.3.0" "2.2.6")
-assert_eq "default: download-key" \
-  "composer | v5.8 | _mageos | 2.2.6 | 8.3.0" \
+# Default cache key (Linux)
+OUT=$(bash "$SCRIPT" "_mageos" "Linux" "8.3.0" "2.2.6")
+assert_eq "linux: download-key" \
+  "composer | v5.8 | Linux | _mageos | 2.2.6 | 8.3.0" \
+  "$(field "$OUT" download-key)"
+
+# OS segment differentiates macOS from Linux
+OUT=$(bash "$SCRIPT" "_mageos" "macOS" "8.3.0" "2.2.6")
+assert_eq "macos: download-key" \
+  "composer | v5.8 | macOS | _mageos | 2.2.6 | 8.3.0" \
   "$(field "$OUT" download-key)"
 
 # Custom composer_cache_key
-OUT=$(bash "$SCRIPT" "custom-v2" "8.1.5" "2.4.2")
+OUT=$(bash "$SCRIPT" "custom-v2" "Linux" "8.1.5" "2.4.2")
 assert_eq "custom key: download-key" \
-  "composer | v5.8 | custom-v2 | 2.4.2 | 8.1.5" \
+  "composer | v5.8 | Linux | custom-v2 | 2.4.2 | 8.1.5" \
   "$(field "$OUT" download-key)"
 
 echo ""