diff --git a/Library/Homebrew/diagnostic.rb b/Library/Homebrew/diagnostic.rb
index 7253e9bc2a..edc2d4c33d 100644
--- a/Library/Homebrew/diagnostic.rb
+++ b/Library/Homebrew/diagnostic.rb
@@ -611,7 +611,7 @@ module Homebrew
 
         <<~EOS
           You have the following deprecated, official taps tapped:
-            Homebrew/homebrew-#{tapped_deprecated_taps.join("\n  ")}
+            Homebrew/homebrew-#{tapped_deprecated_taps.join("\n  Homebrew/homebrew-")}
           Untap them with `brew untap`.
         EOS
       end