diff --git a/Library/Homebrew/hardware.rb b/Library/Homebrew/hardware.rb
index 1bdfe99a78..0cbcac435f 100644
--- a/Library/Homebrew/hardware.rb
+++ b/Library/Homebrew/hardware.rb
@@ -80,6 +80,8 @@ module Hardware
       end
 
       def universal_archs
+        odeprecated "Hardware::CPU.universal_archs"
+
         [arch].extend ArchitectureListExtension
       end
 
diff --git a/Library/Homebrew/os/mac/architecture_list.rb b/Library/Homebrew/os/mac/architecture_list.rb
index f7cca8d697..1268a7a646 100644
--- a/Library/Homebrew/os/mac/architecture_list.rb
+++ b/Library/Homebrew/os/mac/architecture_list.rb
@@ -1,6 +1,8 @@
 # typed: false
 # frozen_string_literal: true
 
+# TODO: (3.2) remove this module when the linked deprecated functions are removed.
+
 require "hardware"
 
 module ArchitectureListExtension
diff --git a/Library/Homebrew/os/mac/mach.rb b/Library/Homebrew/os/mac/mach.rb
index 7a6a75c318..ff0b1c74c3 100644
--- a/Library/Homebrew/os/mac/mach.rb
+++ b/Library/Homebrew/os/mac/mach.rb
@@ -67,6 +67,7 @@ module MachOShim
   end
 
   def archs
+    # TODO: (3.2) remove ArchitectureListExtension
     mach_data.map { |m| m.fetch :arch }.extend(ArchitectureListExtension)
   end
 
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index 1a22c41823..553ed7524c 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -384,6 +384,8 @@ module Kernel
 
   # Returns array of architectures that the given command or library is built for.
   def archs_for_command(cmd)
+    odeprecated "archs_for_command"
+
     cmd = which(cmd) unless Pathname.new(cmd).absolute?
     Pathname.new(cmd).archs
   end