diff --git a/app/models/global_setting.rb b/app/models/global_setting.rb
index f0fb74b5a38..c81430d2cd5 100644
--- a/app/models/global_setting.rb
+++ b/app/models/global_setting.rb
@@ -85,6 +85,10 @@ class GlobalSetting
       end) == :true
   end
 
+  def self.s3_bucket_name
+    @s3_bucket_name ||= s3_bucket.downcase.split("/")[0]
+  end
+
   # for testing
   def self.reset_s3_cache!
     @use_s3 = nil
diff --git a/app/models/site_setting.rb b/app/models/site_setting.rb
index 8f8332a39c1..ec8b8e76244 100644
--- a/app/models/site_setting.rb
+++ b/app/models/site_setting.rb
@@ -133,7 +133,7 @@ class SiteSetting < ActiveRecord::Base
     end
 
     def self.absolute_base_url
-      bucket = SiteSetting.enable_s3_uploads ? Discourse.store.s3_bucket_name : GlobalSetting.s3_bucket
+      bucket = SiteSetting.enable_s3_uploads ? Discourse.store.s3_bucket_name : GlobalSetting.s3_bucket_name
 
       # cf. http://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
       if SiteSetting.Upload.s3_region == "us-east-1"