diff --git a/Library/.rubocop.yml b/Library/.rubocop.yml
index 2972ab0bfd..358bafc5a7 100644
--- a/Library/.rubocop.yml
+++ b/Library/.rubocop.yml
@@ -18,6 +18,7 @@ AllCops:
     - 'Homebrew/sorbet/rbi/gems/**/*.rbi'
     - 'Homebrew/sorbet/rbi/hidden-definitions/**/*.rbi'
     - 'Homebrew/sorbet/rbi/todo.rbi'
+    - 'Homebrew/sorbet/rbi/upstream.rbi'
     - 'Homebrew/bin/*'
     - 'Homebrew/vendor/**/*'
 
diff --git a/Library/Homebrew/cask/caskroom.rb b/Library/Homebrew/cask/caskroom.rb
index 4aa3ea067b..8d91d4582f 100644
--- a/Library/Homebrew/cask/caskroom.rb
+++ b/Library/Homebrew/cask/caskroom.rb
@@ -1,4 +1,4 @@
-# typed: false
+# typed: true
 # frozen_string_literal: true
 
 require "utils/user"
@@ -10,13 +10,13 @@ module Cask
   module Caskroom
     extend T::Sig
 
-    module_function
-
-    def path
+    sig { returns(Pathname) }
+    def self.path
       @path ||= HOMEBREW_PREFIX.join("Caskroom")
     end
 
-    def ensure_caskroom_exists
+    sig { void }
+    def self.ensure_caskroom_exists
       return if path.exist?
 
       sudo = !path.parent.writable?
@@ -32,8 +32,8 @@ module Cask
       SystemCommand.run("/usr/bin/chgrp", args: ["admin", path], sudo: sudo)
     end
 
-    sig { params(config: Config).returns(T::Array[Cask]) }
-    def casks(config: nil)
+    sig { params(config: T.nilable(Config)).returns(T::Array[Cask]) }
+    def self.casks(config: nil)
       return [] unless path.exist?
 
       Pathname.glob(path.join("*")).sort.select(&:directory?).map do |path|
diff --git a/Library/Homebrew/sorbet/rbi/upstream.rbi b/Library/Homebrew/sorbet/rbi/upstream.rbi
new file mode 100644
index 0000000000..208f4e3c36
--- /dev/null
+++ b/Library/Homebrew/sorbet/rbi/upstream.rbi
@@ -0,0 +1,7 @@
+# typed: strict
+
+class Pathname
+  # https://github.com/sorbet/sorbet/pull/3676
+  sig { params(p1: T.any(String, Pathname), p2: String).returns(T::Array[Pathname]) }
+  def self.glob(p1, p2 = T.unsafe(nil)); end
+end