diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 87a199240660f..45576361497fe 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,13 @@
+*   Make `ActiveRecord::Encryption::Encryptor` agnostic of the serialization format used for encrypted data.
+
+    Previously, the encryptor instance only allowed an encrypted value serialized as a `String` to be passed to the message serializer.
+
+    Now, the encryptor lets the configured `message_serializer` decide which types of serialized encrypted values are supported. A custom serialiser is therefore allowed to serialize `ActiveRecord::Encryption::Message` objects using a type other than `String`.
+
+    The default `ActiveRecord::Encryption::MessageSerializer` already ensures that only `String` objects are passed for deserialization.
+
+    *Maxime Réty*
+
 *   Fix `encrypted_attribute?` to take into account context properties passed to `encrypts`.
 
     *Maxime Réty*
diff --git a/activerecord/lib/active_record/encryption/encryptor.rb b/activerecord/lib/active_record/encryption/encryptor.rb
index 3c13040cebf0b..1c19d9e5459ae 100644
--- a/activerecord/lib/active_record/encryption/encryptor.rb
+++ b/activerecord/lib/active_record/encryption/encryptor.rb
@@ -100,7 +100,6 @@ def serialize_message(message)
         end
 
         def deserialize_message(message)
-          raise Errors::Encoding unless message.is_a?(String)
           serializer.load message
         rescue ArgumentError, TypeError, Errors::ForbiddenClass
           raise Errors::Encoding
diff --git a/activerecord/test/cases/encryption/encryptor_test.rb b/activerecord/test/cases/encryption/encryptor_test.rb
index 8829a00c58bfc..1195a6cdfa830 100644
--- a/activerecord/test/cases/encryption/encryptor_test.rb
+++ b/activerecord/test/cases/encryption/encryptor_test.rb
@@ -12,7 +12,13 @@ class ActiveRecord::Encryption::EncryptorTest < ActiveRecord::EncryptionTestCase
     assert_encrypt_text("my secret text")
   end
 
-  test "decrypt and invalid string will raise a Decryption error" do
+  test "trying to decrypt something else than a string will raise a Decryption error" do
+    assert_raises(ActiveRecord::Encryption::Errors::Decryption) do
+      @encryptor.decrypt(:it_can_only_decrypt_strings)
+    end
+  end
+
+  test "decrypt an invalid string will raise a Decryption error" do
     assert_raises(ActiveRecord::Encryption::Errors::Decryption) do
       @encryptor.decrypt("some test that does not make sense")
     end
diff --git a/activerecord/test/cases/encryption/message_serializer_test.rb b/activerecord/test/cases/encryption/message_serializer_test.rb
index 1e86b30690782..db81ad74a7f31 100644
--- a/activerecord/test/cases/encryption/message_serializer_test.rb
+++ b/activerecord/test/cases/encryption/message_serializer_test.rb
@@ -29,13 +29,13 @@ class ActiveRecord::Encryption::MessageSerializerTest < ActiveRecord::Encryption
     assert_nothing_raised { @serializer.load(class_loading_payload) }
   end
 
-  test "detects random JSON data and raises an invalid dencryption error" do
+  test "detects random JSON data and raises a decryption error" do
     assert_raises ActiveRecord::Encryption::Errors::Decryption do
       @serializer.load JSON.dump("hey there")
     end
   end
 
-  test "detects random JSON hashes and raises an invalid decryption error" do
+  test "detects random JSON hashes and raises a decryption error" do
     assert_raises ActiveRecord::Encryption::Errors::Decryption do
       @serializer.load JSON.dump({ some: "other data" })
     end
@@ -47,6 +47,12 @@ class ActiveRecord::Encryption::MessageSerializerTest < ActiveRecord::Encryption
     end
   end
 
+  test "raises a TypeError when trying to deserialize other data types" do
+    assert_raises TypeError do
+      @serializer.load(:it_can_only_deserialize_strings)
+    end
+  end
+
   test "raises ForbiddenClass when trying to serialize other data types" do
     assert_raises ActiveRecord::Encryption::Errors::ForbiddenClass do
       @serializer.dump("it can only serialize messages!")
diff --git a/guides/source/active_record_encryption.md b/guides/source/active_record_encryption.md
index f0c43105c8f5d..5aa20d5586762 100644
--- a/guides/source/active_record_encryption.md
+++ b/guides/source/active_record_encryption.md
@@ -145,7 +145,7 @@ To encrypt Action Text fixtures, you should place them in `fixtures/action_text/
 
 ### Supported Types
 
-`active_record.encryption` will serialize values using the underlying type before encrypting them, but *they must be serializable as strings*. Structured types like `serialized` are supported out of the box.
+`active_record.encryption` will serialize values using the underlying type before encrypting them, but, unless using a custom `message_serializer`, *they must be serializable as strings*. Structured types like `serialized` are supported out of the box.
 
 If you need to support a custom type, the recommended way is using a [serialized attribute](https://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/Serialization/ClassMethods.html). The declaration of the serialized attribute should go **before** the encryption declaration: