diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index 5f1d5433f64..806cf8ebd9b 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -16,7 +16,8 @@ permissions:
 
 jobs:
   benchmark:
-    runs-on: ubuntu-latest
+    # ruby/setup-ruby has no Ruby < 3.2 for ubuntu-26.04, which ubuntu-latest now points to
+    runs-on: ${{ matrix.ruby < 3.2 && 'ubuntu-24.04' || 'ubuntu-latest' }}
     env:
       GH_EVENT: ${{github.event_name}}
       GH_REF: ${{github.head_ref}}
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3eff6db2efb..b59d1bcff0f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -45,7 +45,8 @@ jobs:
         run: bundle exec rake rbs:test
 
   test:
-    runs-on: ubuntu-latest
+    # ruby/setup-ruby has no Ruby < 3.2 for ubuntu-26.04, which ubuntu-latest now points to
+    runs-on: ${{ matrix.ruby < 3.2 && 'ubuntu-24.04' || 'ubuntu-latest' }}
     strategy:
       fail-fast: false
       matrix: