diff --git a/.github/workflows/smithy-polymorph.yml b/.github/workflows/smithy-polymorph.yml
index d77cadfea..002bd09a1 100644
--- a/.github/workflows/smithy-polymorph.yml
+++ b/.github/workflows/smithy-polymorph.yml
@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-12]
+        os: [ubuntu-latest, windows-latest, macos-13]
     runs-on: ${{matrix.os}}
     steps:
       - uses: actions/checkout@v3