diff --git a/lib/mastodon/cli/maintenance.rb b/lib/mastodon/cli/maintenance.rb
index 9cc9a3507..a95b7a30c 100644
--- a/lib/mastodon/cli/maintenance.rb
+++ b/lib/mastodon/cli/maintenance.rb
@@ -136,24 +136,24 @@ module Mastodon::CLI
       Mastodon has to be stopped to run this task, which will take a long time and may be destructive.
     LONG_DESC
     def fix_duplicates
-      if ActiveRecord::Migrator.current_version < MIN_SUPPORTED_VERSION
-        say 'Your version of the database schema is too old and is not supported by this script.', :red
-        say 'Please update to at least Mastodon 3.0.0 before running this script.', :red
-        exit(1)
-      elsif ActiveRecord::Migrator.current_version > MAX_SUPPORTED_VERSION
-        say 'Your version of the database schema is more recent than this script, this may cause unexpected errors.', :yellow
-        exit(1) unless yes?('Continue anyway? (Yes/No)')
-      end
+      verify_system_ready!
 
-      if Sidekiq::ProcessSet.new.any?
-        say 'It seems Sidekiq is running. All Mastodon processes need to be stopped when using this script.', :red
-        exit(1)
-      end
+      process_deduplications
 
-      say 'This task will take a long time to run and is potentially destructive.', :yellow
-      say 'Please make sure to stop Mastodon and have a backup.', :yellow
-      exit(1) unless yes?('Continue? (Yes/No)')
+      deduplication_cleanup_tasks
 
+      say 'Finished!'
+    end
+
+    private
+
+    def verify_system_ready!
+      verify_schema_version!
+      verify_sidekiq_not_active!
+      verify_backup_warning!
+    end
+
+    def process_deduplications
       deduplicate_users!
       deduplicate_account_domain_blocks!
       deduplicate_account_identity_proofs!
@@ -173,14 +173,44 @@ module Mastodon::CLI
       deduplicate_webauthn_credentials!
       deduplicate_webhooks!
       deduplicate_software_updates!
-
-      Scenic.database.refresh_materialized_view('instances', concurrently: true, cascade: false) if ActiveRecord::Migrator.current_version >= 2020_12_06_004238
-      Rails.cache.clear
-
-      say 'Finished!'
     end
 
-    private
+    def deduplication_cleanup_tasks
+      refresh_instances_view if schema_has_instances_view?
+      Rails.cache.clear
+    end
+
+    def refresh_instances_view
+      Scenic.database.refresh_materialized_view('instances', concurrently: true, cascade: false)
+    end
+
+    def schema_has_instances_view?
+      ActiveRecord::Migrator.current_version >= 2020_12_06_004238
+    end
+
+    def verify_schema_version!
+      if ActiveRecord::Migrator.current_version < MIN_SUPPORTED_VERSION
+        say 'Your version of the database schema is too old and is not supported by this script.', :red
+        say 'Please update to at least Mastodon 3.0.0 before running this script.', :red
+        exit(1)
+      elsif ActiveRecord::Migrator.current_version > MAX_SUPPORTED_VERSION
+        say 'Your version of the database schema is more recent than this script, this may cause unexpected errors.', :yellow
+        exit(1) unless yes?('Continue anyway? (Yes/No)')
+      end
+    end
+
+    def verify_sidekiq_not_active!
+      if Sidekiq::ProcessSet.new.any?
+        say 'It seems Sidekiq is running. All Mastodon processes need to be stopped when using this script.', :red
+        exit(1)
+      end
+    end
+
+    def verify_backup_warning!
+      say 'This task will take a long time to run and is potentially destructive.', :yellow
+      say 'Please make sure to stop Mastodon and have a backup.', :yellow
+      exit(1) unless yes?('Continue? (Yes/No)')
+    end
 
     def deduplicate_accounts!
       remove_index_if_exists!(:accounts, 'index_accounts_on_username_and_domain_lower')
diff --git a/spec/lib/mastodon/cli/maintenance_spec.rb b/spec/lib/mastodon/cli/maintenance_spec.rb
index 12cd9ca8a..a6789ea5a 100644
--- a/spec/lib/mastodon/cli/maintenance_spec.rb
+++ b/spec/lib/mastodon/cli/maintenance_spec.rb
@@ -4,9 +4,51 @@ require 'rails_helper'
 require 'mastodon/cli/maintenance'
 
 describe Mastodon::CLI::Maintenance do
+  let(:cli) { described_class.new }
+
   describe '.exit_on_failure?' do
     it 'returns true' do
       expect(described_class.exit_on_failure?).to be true
     end
   end
+
+  describe '#fix_duplicates' do
+    context 'when the database version is too old' do
+      before do
+        allow(ActiveRecord::Migrator).to receive(:current_version).and_return(2000_01_01_000000) # Earlier than minimum
+      end
+
+      it 'Exits with error message' do
+        expect { cli.invoke :fix_duplicates }.to output(
+          a_string_including('is too old')
+        ).to_stdout.and raise_error(SystemExit)
+      end
+    end
+
+    context 'when the database version is too new and the user does not continue' do
+      before do
+        allow(ActiveRecord::Migrator).to receive(:current_version).and_return(2100_01_01_000000) # Later than maximum
+        allow(cli.shell).to receive(:yes?).with('Continue anyway? (Yes/No)').and_return(false).once
+      end
+
+      it 'Exits with error message' do
+        expect { cli.invoke :fix_duplicates }.to output(
+          a_string_including('more recent')
+        ).to_stdout.and raise_error(SystemExit)
+      end
+    end
+
+    context 'when Sidekiq is running' do
+      before do
+        allow(ActiveRecord::Migrator).to receive(:current_version).and_return(2022_01_01_000000) # Higher than minimum, lower than maximum
+        allow(Sidekiq::ProcessSet).to receive(:new).and_return [:process]
+      end
+
+      it 'Exits with error message' do
+        expect { cli.invoke :fix_duplicates }.to output(
+          a_string_including('Sidekiq is running')
+        ).to_stdout.and raise_error(SystemExit)
+      end
+    end
+  end
 end