diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ff04826..64b71a3 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -1,7 +1,9 @@
 name: re2 Tests
+
 concurrency:
   group: "${{github.workflow}}-${{github.sha}}"
   cancel-in-progress: true
+
 on:
   workflow_dispatch:
   push:
@@ -9,6 +11,9 @@ on:
       - main
   pull_request:
 
+env:
+  RUBYOPT: "--enable-frozen-string-literal --debug-frozen-string-literal --debug"
+
 jobs:
   build-cruby-gem:
     name: "Build CRuby gem"