diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index a4a70c8..cf3b044 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,19 +16,27 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ['3.2', '3.3', '3.4']
-        rails: ['7.1.0', '7.2.0', '8.0.0']
+        ruby: ['3.3', '3.4', '4.0']
+        rails: ['7.2.0', '8.0.0', '8.1.0']
         activeadmin: ['3.2.0', '3.3.0', '3.4.0', '3.5.1']
         exclude:
+          # ActiveAdmin 3.2.0 predates Rails 8 support.
           - rails: '8.0.0'
             activeadmin: '3.2.0'
+          - rails: '8.1.0'
+            activeadmin: '3.2.0'
         include:
+          # ActiveAdmin 4 requires railties >= 7.2, so cover its floor and the
+          # newest supported Rails releases.
           - ruby: '3.4'
             rails: '7.2.0'
             activeadmin: '4.0.0.beta22'
           - ruby: '3.4'
             rails: '8.0.0'
             activeadmin: '4.0.0.beta22'
+          - ruby: '3.4'
+            rails: '8.1.0'
+            activeadmin: '4.0.0.beta22'
     env:
       RAILS: ${{ matrix.rails }}
       AA: ${{ matrix.activeadmin }}
diff --git a/Gemfile b/Gemfile
index c80ec8a..f9bdef1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,8 +1,8 @@
 source 'https://rubygems.org'
 gemspec
 
-default_rails_version = '7.1.0'
-default_activeadmin_version = '3.2.0'
+default_rails_version = '8.0.0'
+default_activeadmin_version = '3.5.1'
 
 # `~> 4.0.0.beta22` would admit 4.0.0 GA — pin prereleases exactly so the
 # CI cell tests the AA build it claims to test.
diff --git a/active_admin_import.gemspec b/active_admin_import.gemspec
index 196cc63..2e694cb 100644
--- a/active_admin_import.gemspec
+++ b/active_admin_import.gemspec
@@ -9,7 +9,7 @@ Gem::Specification.new do |gem|
   gem.summary = 'ActiveAdmin import based on activerecord-import gem.'
   gem.homepage = 'https://github.com/activeadmin-plugins/active_admin_import'
   gem.license = 'MIT'
-  gem.required_ruby_version = '>= 3.1.0'
+  gem.required_ruby_version = '>= 3.3.0'
   gem.files = `git ls-files`.split($OUTPUT_RECORD_SEPARATOR)
   gem.executables = gem.files.grep(%r{^bin/}).map { |f| File.basename(f) }
   gem.name = 'active_admin_import'
diff --git a/tasks/test.rake b/tasks/test.rake
index 8c74714..e07f606 100644
--- a/tasks/test.rake
+++ b/tasks/test.rake
@@ -24,7 +24,16 @@ task :setup do
   )
   # v4 drops sprockets-rails (see Gemfile), so skip the asset pipeline to
   # avoid the auto-generated `config/initializers/assets.rb` crashing at boot.
-  rails_new_opts.unshift('--skip-asset-pipeline') if aa_v4
+  if aa_v4
+    rails_new_opts.unshift('--skip-asset-pipeline')
+  else
+    # Rails 8.1 wires importmap-rails into the generated ApplicationController
+    # (`stale_when_importmap_changes`). The AA 3 app uses Sprockets, not
+    # importmap, so that gem is absent and the controller raises NameError at
+    # boot. Skip JavaScript so the macro is never generated — the specs run on
+    # rack_test and never execute JS anyway.
+    rails_new_opts.unshift('--skip-javascript')
+  end
 
   system "bundle exec rails new spec/rails/#{TestAppPaths.app_dir_name} #{rails_new_opts.join(' ')}"
 end