diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5e0f878..ad8edba 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-22.04, ubuntu-24.04, ubuntu-22.04-arm, ubuntu-24.04-arm, macos-13, macos-14, macos-15, macos-15-intel, windows-2022, windows-2025, windows-11-arm ]
+        os: [ ubuntu-22.04, ubuntu-24.04, ubuntu-22.04-arm, ubuntu-24.04-arm, macos-14, macos-15, macos-15-intel, windows-2022, windows-2025, windows-11-arm ]
         ruby: [
           '1.9', '2.0', '2.1', '2.2', '2.3', '2.4', '2.5', '2.6', '2.7', '3.0', '3.1', '3.2', '3.3', '3.4', '4.0', ruby-head,
           jruby-9.4, jruby, jruby-head,
diff --git a/README.md b/README.md
index e9ea56f..2283cbd 100644
--- a/README.md
+++ b/README.md
@@ -50,7 +50,7 @@ The action works on these [GitHub-hosted runners](https://docs.github.com/en/act
 | Operating System | Supported |
 | ---------------- | --------- |
 | Ubuntu  | `ubuntu-22.04`, `ubuntu-24.04`, `ubuntu-22.04-arm`, `ubuntu-24.04-arm` |
-| macOS   | `macos-13` and newer versions |
+| macOS   | `macos-14` and newer versions |
 | Windows | `windows-2022`, `windows-2025`, `windows-11-arm` |
 
 Not all combinations of runner images and versions are supported.
diff --git a/dist/index.js b/dist/index.js
index 5e0aa86..b809cfb 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -85453,7 +85453,7 @@ function validateRubyEngineAndVersion(platform, engineVersions, engine, parsedVe
   // Well known version-platform combinations which do not work:
   if (engine === 'ruby' && platform.startsWith('macos') && os.arch() === 'arm64' && common.floatVersion(version) < 2.6) {
     throw new Error(`CRuby < 2.6 does not support macos-arm64.
-        Either use a newer Ruby version or use a macOS image running on amd64, e.g., macos-13.
+        Either use a newer Ruby version or use a macOS image running on amd64, e.g., macos-15-intel.
         Note that GitHub changed the meaning of macos-latest from macos-12 (amd64) to macos-14 (arm64):
         https://github.blog/changelog/2024-04-01-macos-14-sonoma-is-generally-available-and-the-latest-macos-runner-image/
 
@@ -85466,8 +85466,8 @@ function validateRubyEngineAndVersion(platform, engineVersions, engine, parsedVe
           - { os: macos-latest, ruby: '2.4' }
           - { os: macos-latest, ruby: '2.5' }
           include:
-          - { os: macos-13, ruby: '2.4' }
-          - { os: macos-13, ruby: '2.5' }
+          - { os: macos-15-intel, ruby: '2.4' }
+          - { os: macos-15-intel, ruby: '2.5' }
 
         But of course you should consider dropping support for these long-EOL Rubies, which cannot even be built on recent macOS machines.`)
   } else if (engine === 'truffleruby' && platform.startsWith('windows')) {
diff --git a/index.js b/index.js
index 62e46fe..d6fc89c 100644
--- a/index.js
+++ b/index.js
@@ -175,7 +175,7 @@ function validateRubyEngineAndVersion(platform, engineVersions, engine, parsedVe
   // Well known version-platform combinations which do not work:
   if (engine === 'ruby' && platform.startsWith('macos') && os.arch() === 'arm64' && common.floatVersion(version) < 2.6) {
     throw new Error(`CRuby < 2.6 does not support macos-arm64.
-        Either use a newer Ruby version or use a macOS image running on amd64, e.g., macos-13.
+        Either use a newer Ruby version or use a macOS image running on amd64, e.g., macos-15-intel.
         Note that GitHub changed the meaning of macos-latest from macos-12 (amd64) to macos-14 (arm64):
         https://github.blog/changelog/2024-04-01-macos-14-sonoma-is-generally-available-and-the-latest-macos-runner-image/
 
@@ -188,8 +188,8 @@ function validateRubyEngineAndVersion(platform, engineVersions, engine, parsedVe
           - { os: macos-latest, ruby: '2.4' }
           - { os: macos-latest, ruby: '2.5' }
           include:
-          - { os: macos-13, ruby: '2.4' }
-          - { os: macos-13, ruby: '2.5' }
+          - { os: macos-15-intel, ruby: '2.4' }
+          - { os: macos-15-intel, ruby: '2.5' }
 
         But of course you should consider dropping support for these long-EOL Rubies, which cannot even be built on recent macOS machines.`)
   } else if (engine === 'truffleruby' && platform.startsWith('windows')) {