diff --git a/Library/Homebrew/keg.rb b/Library/Homebrew/keg.rb
index f878f60f83..8ea2c98f85 100644
--- a/Library/Homebrew/keg.rb
+++ b/Library/Homebrew/keg.rb
@@ -1,4 +1,4 @@
-# typed: false
+# typed: true
 # frozen_string_literal: true
 
 require "keg_relocate"
@@ -524,8 +524,8 @@ class Keg
   end
 
   def delete_pyc_files!
-    find { |pn| pn.delete if PYC_EXTENSIONS.include?(pn.extname) }
-    find { |pn| FileUtils.rm_rf pn if pn.basename.to_s == "__pycache__" }
+    path.find { |pn| pn.delete if PYC_EXTENSIONS.include?(pn.extname) }
+    path.find { |pn| FileUtils.rm_rf pn if pn.basename.to_s == "__pycache__" }
   end
 
   def binary_executable_or_library_files
diff --git a/Library/Homebrew/mktemp.rb b/Library/Homebrew/mktemp.rb
index 8e6e9b0883..159c0b88df 100644
--- a/Library/Homebrew/mktemp.rb
+++ b/Library/Homebrew/mktemp.rb
@@ -1,4 +1,4 @@
-# typed: false
+# typed: true
 # frozen_string_literal: true
 
 # Performs {Formula#mktemp}'s functionality, and tracks the results.
@@ -70,7 +70,7 @@ class Mktemp
     begin
       chown(nil, group_id, @tmpdir)
     rescue Errno::EPERM
-      opoo "Failed setting group \"#{Etc.getgrgid(group_id).name}\" on #{@tmpdir}"
+      opoo "Failed setting group \"#{T.must(Etc.getgrgid(group_id)).name}\" on #{@tmpdir}"
     end
 
     begin
diff --git a/Library/Homebrew/options.rb b/Library/Homebrew/options.rb
index 727a72cfa5..e1877729a0 100644
--- a/Library/Homebrew/options.rb
+++ b/Library/Homebrew/options.rb
@@ -1,4 +1,4 @@
-# typed: false
+# typed: true
 # frozen_string_literal: true
 
 # A formula option.
diff --git a/Library/Homebrew/options.rbi b/Library/Homebrew/options.rbi
new file mode 100644
index 0000000000..b11d6cd088
--- /dev/null
+++ b/Library/Homebrew/options.rbi
@@ -0,0 +1,8 @@
+# typed: strict
+
+class Options
+  # This is a workaround to enable `alias to_ary to_a`
+  # @see https://github.com/sorbet/sorbet/issues/2378#issuecomment-569474238
+  sig { returns(T::Array[Option]) }
+  def to_a; end
+end
diff --git a/Library/Homebrew/os/linux/elf.rb b/Library/Homebrew/os/linux/elf.rb
index cdfc602fba..ca7d078b89 100644
--- a/Library/Homebrew/os/linux/elf.rb
+++ b/Library/Homebrew/os/linux/elf.rb
@@ -1,4 +1,4 @@
-# typed: false
+# typed: true
 # frozen_string_literal: true
 
 # {Pathname} extension for dealing with ELF files.
diff --git a/Library/Homebrew/os/linux/elf.rbi b/Library/Homebrew/os/linux/elf.rbi
new file mode 100644
index 0000000000..2c99175895
--- /dev/null
+++ b/Library/Homebrew/os/linux/elf.rbi
@@ -0,0 +1,5 @@
+# typed: strict
+
+module ELFShim
+  requires_ancestor { Pathname }
+end
diff --git a/Library/Homebrew/os/mac/mach.rb b/Library/Homebrew/os/mac/mach.rb
index abadcf8fd6..b421103de7 100644
--- a/Library/Homebrew/os/mac/mach.rb
+++ b/Library/Homebrew/os/mac/mach.rb
@@ -1,4 +1,4 @@
-# typed: false
+# typed: true
 # frozen_string_literal: true
 
 require "macho"
diff --git a/Library/Homebrew/os/mac/mach.rbi b/Library/Homebrew/os/mac/mach.rbi
new file mode 100644
index 0000000000..54bb844d78
--- /dev/null
+++ b/Library/Homebrew/os/mac/mach.rbi
@@ -0,0 +1,5 @@
+# typed: strict
+
+module MachOShim
+  include Kernel
+end