diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 3873080..1679d31 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,4 +1,4 @@
-name: ubuntu
+name: CI
 
 on: [push]
 
@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ 'ubuntu-latest', 'macos-latest', 'windows-latest' ]
-        ruby: [ 'head', '2.7', '2.6', '2.5' ]
+        ruby: [ 'head', '3.0', '2.7', '2.6', '2.5' ]
     steps:
     - uses: actions/checkout@v2
     - name: Set up Ruby
diff --git a/README.md b/README.md
index bc393fe..ffb8ff9 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # Prime
 
+[![CI](https://github.com/ruby/prime/actions/workflows/test.yml/badge.svg)](https://github.com/ruby/prime/actions/workflows/test.yml)
+
 Prime numbers and factorization library.
 
 ## Installation