diff --git a/config/initializers/constants.rb b/config/initializers/constants.rb
index 54c5e5378..b1b035f19 100644
--- a/config/initializers/constants.rb
+++ b/config/initializers/constants.rb
@@ -325,6 +325,7 @@ class Constants
   config[:attributes][:all] << 'id'
   config[:attributes][:all] << 'contenteditable'
   config[:attributes]['img'] << 'data-mce-token'
+  config[:attributes]['img'] << 'data-source-type'
   config[:protocols]['img']['src'] << 'data'
   INPUT_SANITIZE_CONFIG = Sanitize::Config.freeze_config(config)