diff --git a/Library/Homebrew/update_migrator.rb b/Library/Homebrew/update_migrator.rb
index 5a04fb6b1f..5351385973 100644
--- a/Library/Homebrew/update_migrator.rb
+++ b/Library/Homebrew/update_migrator.rb
@@ -85,7 +85,9 @@ module UpdateMigrator
           path.children
               .reject(&:symlink?)
               .select(&:file?)
-              .map { |child| child.basename.to_s.sub(/\-\-.*/, "") }
+              .map { |child| child.basename.to_s }
+              .select { |basename| basename.include?("--") }
+              .map { |basename| basename.sub(/\-\-.*/, "") }
               .uniq
         else
           []