diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d50ff2a..f17ddb1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -24,6 +24,8 @@ jobs:
             gemfile: Gemfile.8.0.sqlite3
           - ruby: "3.4.7"
             gemfile: Gemfile.8.1.sqlite3
+          - ruby: "4.0.1"
+            gemfile: Gemfile.8.1.sqlite3
     env:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
 
diff --git a/Gemfile.8.1.sqlite3.lock b/Gemfile.8.1.sqlite3.lock
index 3816fe1..1998e21 100644
--- a/Gemfile.8.1.sqlite3.lock
+++ b/Gemfile.8.1.sqlite3.lock
@@ -37,7 +37,9 @@ GEM
       concurrent-ruby (~> 1.0)
     json (2.15.1)
     logger (1.7.0)
-    minitest (5.26.0)
+    minitest (6.0.1)
+      prism (~> 1.5)
+    prism (1.8.0)
     rake (13.3.0)
     rspec (3.13.2)
       rspec-core (~> 3.13.0)
@@ -53,16 +55,16 @@ GEM
       rspec-support (~> 3.13.0)
     rspec-support (3.13.6)
     securerandom (0.4.1)
-    sqlite3 (2.7.4-aarch64-linux-gnu)
-    sqlite3 (2.7.4-aarch64-linux-musl)
-    sqlite3 (2.7.4-arm-linux-gnu)
-    sqlite3 (2.7.4-arm-linux-musl)
-    sqlite3 (2.7.4-arm64-darwin)
-    sqlite3 (2.7.4-x86-linux-gnu)
-    sqlite3 (2.7.4-x86-linux-musl)
-    sqlite3 (2.7.4-x86_64-darwin)
-    sqlite3 (2.7.4-x86_64-linux-gnu)
-    sqlite3 (2.7.4-x86_64-linux-musl)
+    sqlite3 (2.9.0-aarch64-linux-gnu)
+    sqlite3 (2.9.0-aarch64-linux-musl)
+    sqlite3 (2.9.0-arm-linux-gnu)
+    sqlite3 (2.9.0-arm-linux-musl)
+    sqlite3 (2.9.0-arm64-darwin)
+    sqlite3 (2.9.0-x86-linux-gnu)
+    sqlite3 (2.9.0-x86-linux-musl)
+    sqlite3 (2.9.0-x86_64-darwin)
+    sqlite3 (2.9.0-x86_64-linux-gnu)
+    sqlite3 (2.9.0-x86_64-linux-musl)
     timeout (0.4.3)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
@@ -89,4 +91,4 @@ DEPENDENCIES
   sqlite3
 
 BUNDLED WITH
-   2.5.6
+   4.0.4
diff --git a/spec/active_type/object_spec.rb b/spec/active_type/object_spec.rb
index cc25dba..126b232 100644
--- a/spec/active_type/object_spec.rb
+++ b/spec/active_type/object_spec.rb
@@ -1,5 +1,4 @@
 require 'spec_helper'
-require 'ostruct'
 
 module ObjectSpec
 
@@ -255,9 +254,8 @@ class ObjectWithUnsupportedTypes < Object
       subject.virtual_time = t
       subject.virtual_date = Date.today
       subject.virtual_boolean = true
-      subject.virtual_attribute = OpenStruct.new({:test => "openstruct"})
 
-      expect(subject.inspect).to eq("#<ObjectSpec::Object virtual_attribute: #<OpenStruct test=\"openstruct\">, virtual_boolean: true, virtual_date: \"#{Date.today}\", virtual_integer: 17, virtual_string: \"string\", virtual_time: \"#{t.to_formatted_s(:db)}\", virtual_type_attribute: nil>")
+      expect(subject.inspect).to eq("#<ObjectSpec::Object virtual_attribute: nil, virtual_boolean: true, virtual_date: \"#{Date.today}\", virtual_integer: 17, virtual_string: \"string\", virtual_time: \"#{t.to_formatted_s(:db)}\", virtual_type_attribute: nil>")
     end
 
   end
diff --git a/spec/active_type/record_spec.rb b/spec/active_type/record_spec.rb
index 10b9b4d..32bd2c6 100644
--- a/spec/active_type/record_spec.rb
+++ b/spec/active_type/record_spec.rb
@@ -1,5 +1,4 @@
 require 'spec_helper'
-require 'ostruct'
 
 module RecordSpec
 
@@ -203,9 +202,8 @@ class RecordWithOptionalBelongsToFlippedValidatesForeignKey < Record
       subject.virtual_time = t
       subject.virtual_date = Date.today
       subject.virtual_boolean = true
-      subject.virtual_attribute = OpenStruct.new({:test => "openstruct"})
 
-      expect(subject.inspect).to eq("#<RecordSpec::Record id: nil, persisted_boolean: nil, persisted_date: nil, persisted_integer: 20, persisted_string: \"persisted string\", persisted_time: nil, virtual_attribute: #<OpenStruct test=\"openstruct\">, virtual_boolean: true, virtual_date: \"#{Date.today}\", virtual_integer: 17, virtual_string: \"string\", virtual_time: \"#{t.to_formatted_s(:db)}\", virtual_type_attribute: nil>")
+      expect(subject.inspect).to eq("#<RecordSpec::Record id: nil, persisted_boolean: nil, persisted_date: nil, persisted_integer: 20, persisted_string: \"persisted string\", persisted_time: nil, virtual_attribute: nil, virtual_boolean: true, virtual_date: \"#{Date.today}\", virtual_integer: 17, virtual_string: \"string\", virtual_time: \"#{t.to_formatted_s(:db)}\", virtual_type_attribute: nil>")
     end
 
   end