diff --git a/Library/Homebrew/rubocops/shared/url_helper.rb b/Library/Homebrew/rubocops/shared/url_helper.rb
index 1d5e6a32ff..0a49816f13 100644
--- a/Library/Homebrew/rubocops/shared/url_helper.rb
+++ b/Library/Homebrew/rubocops/shared/url_helper.rb
@@ -35,6 +35,12 @@ module RuboCop
       def audit_url(type, urls, mirrors, livecheck_url: false)
         @type = type
 
+        # URLs must be ASCII; IDNs must be punycode
+        ascii_pattern = /[^\p{ASCII}]+/
+        audit_urls(urls, ascii_pattern) do |_, url|
+          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|
diff --git a/Library/Homebrew/test/rubocops/urls_spec.rb b/Library/Homebrew/test/rubocops/urls_spec.rb
index 80bf49199a..fab6d84ada 100644
--- a/Library/Homebrew/test/rubocops/urls_spec.rb
+++ b/Library/Homebrew/test/rubocops/urls_spec.rb
@@ -177,6 +177,14 @@ RSpec.describe RuboCop::Cop::FormulaAudit::Urls do
       "url" => "svn+http://brew.sh/foo/bar",
       "msg" => "Use of the svn+http:// scheme is deprecated, pass `:using => :svn` instead",
       "col" => 2,
+    }, {
+      "url" => "https://🫠.sh/foo/bar",
+      "msg" => "Please use the ASCII (Punycode encoded host, URL-encoded path and query) version of https://🫠.sh/foo/bar.",
+      "col" => 2,
+    }, {
+      "url" => "https://ßreｗ.sh/foo/bar",
+      "msg" => "Please use the ASCII (Punycode encoded host, URL-encoded path and query) version of https://ßreｗ.sh/foo/bar.",
+      "col" => 2,
     }]
   end