diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 4a8d6368..1e516546 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -18,6 +18,7 @@ jobs:
           - "3.2"
           - "3.3"
           - "3.4"
+          - "4.0"
     steps:
       - uses: actions/checkout@v6
       - uses: ruby/setup-ruby@v1
diff --git a/test/test-expression.rb b/test/test-expression.rb
index 8d290976..f4c23be7 100644
--- a/test/test-expression.rb
+++ b/test/test-expression.rb
@@ -135,7 +135,7 @@ def test_snippet_without_tags
     expression.parse("ラングバ", :default_column => name)
     expression.compile
 
-    snippet = expression.snippet([], :width => 30)
+    snippet = expression.snippet([[]], :width => 30)
     assert_equal(["ラングバプロジェクト"],
                  snippet.execute("ラングバプロジェクトはカラムストア機能も"))
     snippet.close