diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index c8347330d..7a39442b8 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -1105,7 +1105,7 @@ en:
     warn_reviving_old_topic_age: "When someone starts replying to a topic where the last reply is older than this many days, a warning will be displayed. Disable by setting to 0."
     autohighlight_all_code: "Force apply code highlighting to all preformatted code blocks even when they didn't explicitly specify the language."
 
-    embeddable_host: "Host that can embed the comments from this Discourse forum."
+    embeddable_host: "Host that can embed the comments from this Discourse forum. Hostname only, do not begin with http://"
     feed_polling_enabled: "EMBEDDING ONLY: Whether to embed a RSS/ATOM feed as posts."
     feed_polling_url: "EMBEDDING ONLY: URL of RSS/ATOM feed to embed."
     embed_by_username: "Discourse username of the user who creates the embedded topics."
diff --git a/config/site_settings.yml b/config/site_settings.yml
index d62689a4e..3982f5253 100644
--- a/config/site_settings.yml
+++ b/config/site_settings.yml
@@ -688,7 +688,9 @@ developer:
     client: true
 
 embedding:
-  embeddable_host: ''
+  embeddable_host:
+      default: ''
+      regex: "^(?!http).+" # don't allow this to start with http:// or https://
   feed_polling_enabled: false
   feed_polling_url: ''
   embed_by_username: