diff --git a/app/assets/javascripts/admin/templates/components/site-settings/bool.hbs b/app/assets/javascripts/admin/templates/components/site-settings/bool.hbs
index 1f441c421ce..f1ac669900e 100644
--- a/app/assets/javascripts/admin/templates/components/site-settings/bool.hbs
+++ b/app/assets/javascripts/admin/templates/components/site-settings/bool.hbs
@@ -1,4 +1,5 @@
 <label>
   {{input type="checkbox" checked=enabled}}
   {{{unbound setting.description}}}
+  {{setting-validation-message message=validationMessage}}
 </label>
diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index d4859e82900..d2d86cfa1de 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -96,6 +96,7 @@ en:
       max_username_length_exists: "You cannot set the maximum username length below the longest username."
       max_username_length_range: "You cannot set the maximum below the minimum."
       default_categories_already_selected: "You cannot select a category used in another list."
+      s3_upload_bucket_is_required: "You cannot enable uploads to S3 unless you've provided the 's3_upload_bucket'."
 
   activemodel:
     errors:
diff --git a/lib/site_setting_validations.rb b/lib/site_setting_validations.rb
index 5c5a0917fc2..e69bfc2f95d 100644
--- a/lib/site_setting_validations.rb
+++ b/lib/site_setting_validations.rb
@@ -46,4 +46,8 @@ module SiteSettingValidations
     validate_default_categories(new_val, default_categories_selected)
   end
 
+  def validate_enable_s3_uploads(new_val)
+    validate_error :s3_upload_bucket_is_required if new_val == "t" && SiteSetting.s3_upload_bucket.blank?
+  end
+
 end