diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7a4e4f7a..9afa265d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -2,9 +2,9 @@ name: CI
 
 on:
   push:
-    branches: [ main ]
+    branches: [ main, 5-x-stable ]
   pull_request:
-    branches: [ main ]
+    branches: [ main, 5-x-stable ]
 
 env:
   BUNDLE_WITHOUT: "development"
@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: [ ruby-2.6, ruby-2.7, ruby-3.0, ruby-3.1, ruby-3.2 ]
+        ruby: [ ruby-2.6, ruby-2.7, ruby-3.0, ruby-3.1, ruby-3.2, ruby-3.3 ]
         os: [ ubuntu-latest ]
 
     steps:
diff --git a/README.md b/README.md
index 5ac0c511..0d78c0ac 100644
--- a/README.md
+++ b/README.md
@@ -116,6 +116,7 @@ the following Ruby  versions:
 - Ruby 3.0
 - Ruby 3.1
 - Ruby 3.2
+- Ruby 3.3
 
 If something doesn't work on one of these versions, it's a bug.