diff --git a/app/models/concerns/attachable.rb b/app/models/concerns/attachable.rb
index f1a069bcb..ac6c1e33a 100644
--- a/app/models/concerns/attachable.rb
+++ b/app/models/concerns/attachable.rb
@@ -7,8 +7,26 @@ module Attachable
     attr_accessor :cached_attachment
 
     validate :attachment_presence
-    validate :validate_attachment_content_type,         if: -> { attachment.attached? }
-    validate :validate_attachment_size,                 if: -> { attachment.attached? }
+
+    validates :attachment,
+      file_content_type: {
+        allow: ->(record) { record.accepted_content_types },
+        if: -> { association_class && attachment.attached? },
+        message: ->(record, *) do
+          I18n.t("#{record.model_name.plural}.errors.messages.wrong_content_type",
+                 content_type: record.attachment_content_type,
+                 accepted_content_types: record.class.humanized_accepted_content_types)
+        end
+      },
+      file_size: {
+        less_than_or_equal_to: ->(record) { record.max_file_size.megabytes },
+        if: -> { association_class && attachment.attached? },
+        message: ->(record, *) do
+          I18n.t("#{record.model_name.plural}.errors.messages.in_between",
+                 min: "0 Bytes",
+                 max: "#{record.max_file_size} MB")
+        end
+      }
 
     before_validation :set_attachment_from_cached_attachment, if: -> { cached_attachment.present? }
   end
@@ -49,23 +67,6 @@ module Attachable
 
   private
 
-    def validate_attachment_size
-      if association_class && attachment_file_size > max_file_size.megabytes
-        errors.add(:attachment, I18n.t("#{model_name.plural}.errors.messages.in_between",
-                                       min: "0 Bytes",
-                                       max: "#{max_file_size} MB"))
-      end
-    end
-
-    def validate_attachment_content_type
-      if association_class && !accepted_content_types.include?(attachment_content_type)
-        message = I18n.t("#{model_name.plural}.errors.messages.wrong_content_type",
-                         content_type: attachment_content_type,
-                         accepted_content_types: self.class.humanized_accepted_content_types)
-        errors.add(:attachment, message)
-      end
-    end
-
     def attachment_presence
       unless attachment.attached?
         errors.add(:attachment, I18n.t("errors.messages.blank"))
diff --git a/spec/shared/models/document_validations.rb b/spec/shared/models/document_validations.rb
index 194c8fbba..3594b1a57 100644
--- a/spec/shared/models/document_validations.rb
+++ b/spec/shared/models/document_validations.rb
@@ -29,7 +29,7 @@ shared_examples "document validations" do |documentable_factory|
   end
 
   it "is not valid for attachments larger than documentable max_file_size definition" do
-    allow(document).to receive(:attachment_file_size).and_return(maxfilesize.megabytes + 1.byte)
+    allow(document.attachment).to receive(:byte_size).and_return(maxfilesize.megabytes + 1.byte)
     max_size_error_message = "must be in between 0 Bytes and #{maxfilesize} MB"
 
     expect(document).not_to be_valid
diff --git a/spec/shared/models/image_validations.rb b/spec/shared/models/image_validations.rb
index 092372550..ed26d0499 100644
--- a/spec/shared/models/image_validations.rb
+++ b/spec/shared/models/image_validations.rb
@@ -38,7 +38,7 @@ shared_examples "image validations" do |imageable_factory|
 
   it "is not valid for attachments larger than imageable max_file_size definition" do
     larger_size = Setting["uploads.images.max_size"].to_i.megabytes + 1.byte
-    allow(image).to receive(:attachment_file_size).and_return(larger_size)
+    allow(image.attachment).to receive(:byte_size).and_return(larger_size)
 
     expect(image).not_to be_valid
     expect(image.errors[:attachment]).to include "must be in between 0 Bytes and 1 MB"