diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index b50f2c6477..175d00958a 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -502,10 +502,14 @@ class Reporter
   end
 
   def migrate_formula_rename
-    report[:R].each do |old_full_name, new_full_name|
-      old_name = old_full_name.split("/").last
+    Formula.installed.map(&:oldname).compact.each do |old_name|
       next unless (dir = HOMEBREW_CELLAR/old_name).directory? && !dir.subdirs.empty?
 
+      new_name = tap.formula_renames[old_name]
+      next unless new_name
+
+      new_full_name = "#{tap}/#{new_name}"
+
       begin
         f = Formulary.factory(new_full_name)
       rescue Exception => e