diff --git a/Library/Homebrew/rubocops/shared/url_helper.rb b/Library/Homebrew/rubocops/shared/url_helper.rb
index 3919d63469..90174dff41 100644
--- a/Library/Homebrew/rubocops/shared/url_helper.rb
+++ b/Library/Homebrew/rubocops/shared/url_helper.rb
@@ -41,11 +41,11 @@ module RuboCop
           problem "Please use the ASCII (Punycode-encoded host, URL-encoded path and query) version of #{url}."
         end
 
-        # GNU URLs; doesn't apply to mirrors
-        gnu_pattern = %r{^(?:https?|ftp)://ftpmirror\.gnu\.org/(.*)}
-        audit_urls(urls, gnu_pattern) do |match, url|
-          problem "#{url} should be: https://ftp.gnu.org/gnu/#{match[1]}"
-        end
+        # TODO: Re-add the following audit after homebrew/core migration.
+        # gnu_pattern = %r{^(?:https?|ftp)://ftp\.gnu\.org/(.*)}
+        # audit_urls(urls, gnu_pattern) do |match, url|
+        #   problem "#{url} should be: https://ftpmirror.gnu.org/gnu/#{match[1]}"
+        # end
 
         # Fossies upstream requests they aren't used as primary URLs
         # https://github.com/Homebrew/homebrew-core/issues/14486#issuecomment-307753234
diff --git a/Library/Homebrew/test/rubocops/urls_spec.rb b/Library/Homebrew/test/rubocops/urls_spec.rb
index a5574f9ddc..38b7ff25dd 100644
--- a/Library/Homebrew/test/rubocops/urls_spec.rb
+++ b/Library/Homebrew/test/rubocops/urls_spec.rb
@@ -6,12 +6,14 @@ RSpec.describe RuboCop::Cop::FormulaAudit::Urls do
   subject(:cop) { described_class.new }
 
   let(:offense_list) do
+    # TODO: Re-add the following to the offense list after homebrew/core migration.
+    # {
+    #   "url" => "https://ftpmirror.gnu.org/lightning/lightning-2.1.0.tar.gz",
+    #   "msg" => "https://ftpmirror.gnu.org/lightning/lightning-2.1.0.tar.gz should be: " \
+    #            "https://ftp.gnu.org/gnu/lightning/lightning-2.1.0.tar.gz",
+    #   "col" => 2,
+    # }
     [{
-      "url" => "https://ftpmirror.gnu.org/lightning/lightning-2.1.0.tar.gz",
-      "msg" => "https://ftpmirror.gnu.org/lightning/lightning-2.1.0.tar.gz should be: " \
-               "https://ftp.gnu.org/gnu/lightning/lightning-2.1.0.tar.gz",
-      "col" => 2,
-    }, {
       "url" => "https://fossies.org/linux/privat/monit-5.23.0.tar.gz",
       "msg" => "Please don't use \"fossies.org\" in the `url` (using as a mirror is fine)",
       "col" => 2,
@@ -209,10 +211,10 @@ RSpec.describe RuboCop::Cop::FormulaAudit::Urls do
         offenses = inspect_source(source)
 
         expected_offenses.zip(offenses.reverse).each do |expected, actual|
-          expect(actual.message).to eq(expected[:message])
-          expect(actual.severity).to eq(expected[:severity])
-          expect(actual.line).to eq(expected[:line])
-          expect(actual.column).to eq(expected[:column])
+          expect(actual&.message).to eq(expected[:message])
+          expect(actual&.severity).to eq(expected[:severity])
+          expect(actual&.line).to eq(expected[:line])
+          expect(actual&.column).to eq(expected[:column])
         end
       end
     end