diff --git a/gemfiles/5_0_stable.gemfile b/gemfiles/5_0_stable.gemfile
index 0355dc6..5824520 100644
--- a/gemfiles/5_0_stable.gemfile
+++ b/gemfiles/5_0_stable.gemfile
@@ -6,5 +6,6 @@ source 'https://rubygems.org'
 
 gem 'activerecord', '~> 5.0'
 gem 'sqlite3', '~> 1.3.6'
+gem 'concurrent-ruby', '1.3.4', require: false
 
 gemspec path: '../'
diff --git a/gemfiles/5_1_stable.gemfile b/gemfiles/5_1_stable.gemfile
index 8136a1e..dac824d 100644
--- a/gemfiles/5_1_stable.gemfile
+++ b/gemfiles/5_1_stable.gemfile
@@ -5,5 +5,6 @@
 source 'https://rubygems.org'
 
 gem 'activerecord', '~> 5.1'
+gem 'concurrent-ruby', '1.3.4', require: false
 
 gemspec path: '../'
diff --git a/gemfiles/5_2_stable.gemfile b/gemfiles/5_2_stable.gemfile
index 0581ddb..0046544 100644
--- a/gemfiles/5_2_stable.gemfile
+++ b/gemfiles/5_2_stable.gemfile
@@ -5,5 +5,6 @@
 source 'https://rubygems.org'
 
 gem 'activerecord', '~> 5.2'
+gem 'concurrent-ruby', '1.3.4', require: false
 
 gemspec path: '../'
diff --git a/gemfiles/6_0_stable.gemfile b/gemfiles/6_0_stable.gemfile
index 852b24f..5cff700 100644
--- a/gemfiles/6_0_stable.gemfile
+++ b/gemfiles/6_0_stable.gemfile
@@ -5,5 +5,6 @@
 source 'https://rubygems.org'
 
 gem 'activerecord', '~> 6.0'
+gem 'concurrent-ruby', '1.3.4', require: false
 
 gemspec path: '../'
diff --git a/gemfiles/6_1_stable.gemfile b/gemfiles/6_1_stable.gemfile
index 3e16a96..bd42223 100644
--- a/gemfiles/6_1_stable.gemfile
+++ b/gemfiles/6_1_stable.gemfile
@@ -5,5 +5,6 @@
 source 'https://rubygems.org'
 
 gem 'activerecord', '~> 6.1'
+gem 'concurrent-ruby', '1.3.4', require: false
 
 gemspec path: '../'
diff --git a/gemfiles/7_0_stable.gemfile b/gemfiles/7_0_stable.gemfile
index cffa6d1..f112bd2 100644
--- a/gemfiles/7_0_stable.gemfile
+++ b/gemfiles/7_0_stable.gemfile
@@ -5,5 +5,6 @@
 source 'https://rubygems.org'
 
 gem 'activerecord', '~> 7.0'
+gem 'concurrent-ruby', '1.3.4', require: false
 
 gemspec path: '../'
diff --git a/lib/active_record_encrypted_string/type.rb b/lib/active_record_encrypted_string/type.rb
index 4e369d2..64a56bb 100644
--- a/lib/active_record_encrypted_string/type.rb
+++ b/lib/active_record_encrypted_string/type.rb
@@ -36,7 +36,8 @@ def changed_in_place?(raw_old_value, new_value)
 
     def encryptor
       # TODO: rotate
-      ActiveSupport::MessageEncryptor.new(secret, cipher: ActiveRecordEncryptedString.configuration.cipher_alg)
+      @encryptor ||=
+        ActiveSupport::MessageEncryptor.new(secret, cipher: ActiveRecordEncryptedString.configuration.cipher_alg)
     end
 
     def secret