diff --git a/lib/validators/upload_validator.rb b/lib/validators/upload_validator.rb
index e386931d71..985fe928d9 100644
--- a/lib/validators/upload_validator.rb
+++ b/lib/validators/upload_validator.rb
@@ -78,9 +78,10 @@ class Validators::UploadValidator < ActiveModel::Validator
   end
 
   def maximum_file_size(upload, type)
-    max_size_kb = SiteSetting.send("max_#{type}_size_kb").kilobytes
+    max_size_kb = SiteSetting.send("max_#{type}_size_kb")
+    max_size_bytes = max_size_kb.kilobytes
 
-    if upload.filesize > max_size_kb
+    if upload.filesize > max_size_bytes
       message = I18n.t("upload.#{type}s.too_large", max_size_kb: max_size_kb)
       upload.errors.add(:filesize, message)
     end