diff --git a/.github/workflows/selftest.macos-13.yml b/.github/workflows/selftest.macos-13.yml
index ae42cfd..c8ffb47 100644
--- a/.github/workflows/selftest.macos-13.yml
+++ b/.github/workflows/selftest.macos-13.yml
@@ -5,7 +5,7 @@ on:
     - cron: 0 0 1 * *
   push:
     branches:
-      - selftest
+      - update
 jobs:
   build:
     name: ${{ matrix.os }} / GHC ${{ matrix.ghc }}
diff --git a/src/main.ts b/src/main.ts
index 5c70559..bce18ef 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -8,6 +8,8 @@ import { installed, resolve, ResolvedVersion } from './resolve';
 
 async function main() {
   try {
+    await exec(`brew install ghcup`);
+    await exec(`ghcup install ghc`);
     await workaroundRunnerImageIssue7061();
     await addCabalBinToPath();
     const requested = core.getInput('ghc-version');