diff --git a/activestorage/app/models/active_storage/blob.rb b/activestorage/app/models/active_storage/blob.rb
index e7f2615b0f..53aa9f0237 100644
--- a/activestorage/app/models/active_storage/blob.rb
+++ b/activestorage/app/models/active_storage/blob.rb
@@ -35,6 +35,10 @@ class ActiveStorage::Blob < ActiveRecord::Base
 
   scope :unattached, -> { left_joins(:attachments).where(ActiveStorage::Attachment.table_name => { blob_id: nil }) }
 
+  before_destroy(prepend: true) do
+    raise ActiveRecord::InvalidForeignKey if attachments.exists?
+  end
+
   class << self
     # You can used the signed ID of a blob to refer to it on the client side without fear of tampering.
     # This is particularly helpful for direct uploads where the client-side needs to refer to the blob