diff --git a/lib/global_id/signed_global_id.rb b/lib/global_id/signed_global_id.rb
index fc11d8c..68cf02f 100644
--- a/lib/global_id/signed_global_id.rb
+++ b/lib/global_id/signed_global_id.rb
@@ -42,7 +42,7 @@ def verify_with_legacy_self_validated_metadata(sgid, options)
 
         raise_if_expired(metadata['expires_at'])
 
-        metadata['gid'] if pick_purpose(options) == metadata['purpose']
+        metadata['gid'] if pick_purpose(options)&.to_s == metadata['purpose']&.to_s
       rescue ActiveSupport::MessageVerifier::InvalidSignature, ExpiredMessage
         nil
       end
diff --git a/lib/global_id/verifier.rb b/lib/global_id/verifier.rb
index 847966d..f3eac48 100644
--- a/lib/global_id/verifier.rb
+++ b/lib/global_id/verifier.rb
@@ -3,11 +3,11 @@
 class GlobalID
   class Verifier < ActiveSupport::MessageVerifier
     private
-      def encode(data)
+      def encode(data, **)
         ::Base64.urlsafe_encode64(data)
       end
 
-      def decode(data)
+      def decode(data, **)
         ::Base64.urlsafe_decode64(data)
       end
   end
diff --git a/test/cases/railtie_test.rb b/test/cases/railtie_test.rb
index 688d697..fe2fcfb 100644
--- a/test/cases/railtie_test.rb
+++ b/test/cases/railtie_test.rb
@@ -16,6 +16,7 @@ def setup
     @app.config.eager_load = false
     @app.config.logger = Logger.new(nil)
     @app.config.secret_key_base = ('x' * 30)
+    @app.config.active_support.cache_format_version = Rails::VERSION::STRING.to_f
   end
 
   test 'GlobalID.app for Blog::Application defaults to blog' do
diff --git a/test/cases/signed_global_id_test.rb b/test/cases/signed_global_id_test.rb
index b4d384d..f992f7a 100644
--- a/test/cases/signed_global_id_test.rb
+++ b/test/cases/signed_global_id_test.rb
@@ -71,7 +71,9 @@ class SignedGlobalIDPurposeTest < ActiveSupport::TestCase
 
   test 'parse is backwards compatible with the self validated metadata' do
     legacy_sgid = "eyJnaWQiOiJnaWQ6Ly9iY3gvUGVyc29uLzUiLCJwdXJwb3NlIjoibG9naW4iLCJleHBpcmVzX2F0IjpudWxsfQ==--4b9630f3a1fb3d7d6584d95d4fac96433ec2deef"
-    assert_equal @login_sgid, SignedGlobalID.parse(legacy_sgid, for: 'login')
+    parsed_sgid = SignedGlobalID.parse(legacy_sgid, for: :login)
+    assert_equal @login_sgid.uri, parsed_sgid.uri
+    assert_equal @login_sgid.purpose, parsed_sgid.purpose.to_s
   end
 
   test 'equal only with same purpose' do