diff --git a/.github/workflows/gem-push.yml b/.github/workflows/gem-push.yml
index a3f9274..be317fb 100644
--- a/.github/workflows/gem-push.yml
+++ b/.github/workflows/gem-push.yml
@@ -16,6 +16,10 @@ jobs:
       uses: ruby/setup-ruby@a0102e0972be65f351c307e2d64b9314a57c8073 # v1.324.0
       with:
         ruby-version: 2.6.10
+        # This job only runs `gem build` / `gem push`, so it doesn't need Bundler.
+        # Without this, setup-ruby installs the Gemfile.lock BUNDLED WITH version
+        # (2.7.1, which needs Ruby >= 3.2), and that fails on Ruby 2.6.
+        bundler: none
 
     - uses: rubygems/configure-rubygems-credentials@762a4b77c3300434bb57c7ce80b20e36231927aa # v2.0.0
     - name: Build and push gem