diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index c00c9212..c4512830 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu, macos, windows]
-        ruby: [2.5]
+        ruby: ['2.5']
     runs-on: ${{ matrix.os }}-latest
     steps:
       - uses: actions/checkout@v2
@@ -26,7 +26,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu]
-        ruby: [2.3, 2.4, 2.5, 2.6, 2.7, 'ruby-head']
+        ruby: ['2.3', '2.4', '2.5', '2.6', '2.7', '3.0', 'ruby-head']
     runs-on: ${{ matrix.os }}-latest
     steps:
       - uses: actions/checkout@v2
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 607c58e1..c877aedf 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -51,10 +51,10 @@ def binary(str)
           str.force_encoding(Encoding::BINARY)
         end
 
-        def cache_path(dir, file, args = nil)
+        def cache_path(dir, file, args_key = nil)
           hash = fnv1a_64(file)
-          unless args.nil?
-            hash ^= fnv1a_64(Marshal.dump(args))
+          unless args_key .nil?
+            hash ^= fnv1a_64(args_key)
           end
 
           hex = hash.to_s(16)