diff --git a/Library/Homebrew/cmd/postinstall.rb b/Library/Homebrew/cmd/postinstall.rb
index bde90fa8f5..f1f5d72eba 100644
--- a/Library/Homebrew/cmd/postinstall.rb
+++ b/Library/Homebrew/cmd/postinstall.rb
@@ -1,35 +1,33 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
+require "abstract_command"
 require "sandbox"
 require "formula_installer"
-require "cli/parser"
 
 module Homebrew
-  module_function
+  module Cmd
+    class Postinstall < AbstractCommand
+      cmd_args do
+        description <<~EOS
+          Rerun the post-install steps for <formula>.
+        EOS
 
-  sig { returns(CLI::Parser) }
-  def postinstall_args
-    Homebrew::CLI::Parser.new do
-      description <<~EOS
-        Rerun the post-install steps for <formula>.
-      EOS
+        named_args :installed_formula, min: 1
+      end
 
-      named_args :installed_formula, min: 1
-    end
-  end
-
-  def postinstall
-    args = postinstall_args.parse
-
-    args.named.to_resolved_formulae.each do |f|
-      ohai "Postinstalling #{f}"
-      f.install_etc_var
-      if f.post_install_defined?
-        fi = FormulaInstaller.new(f, **{ debug: args.debug?, quiet: args.quiet?, verbose: args.verbose? }.compact)
-        fi.post_install
-      else
-        opoo "#{f}: no `post_install` method was defined in the formula!"
+      sig { override.void }
+      def run
+        args.named.to_resolved_formulae.each do |f|
+          ohai "Postinstalling #{f}"
+          f.install_etc_var
+          if f.post_install_defined?
+            fi = FormulaInstaller.new(f, **{ debug: args.debug?, quiet: args.quiet?, verbose: args.verbose? }.compact)
+            fi.post_install
+          else
+            opoo "#{f}: no `post_install` method was defined in the formula!"
+          end
+        end
       end
     end
   end
diff --git a/Library/Homebrew/postinstall.rb b/Library/Homebrew/postinstall.rb
index 4b188af9f4..171f54b389 100644
--- a/Library/Homebrew/postinstall.rb
+++ b/Library/Homebrew/postinstall.rb
@@ -12,13 +12,13 @@ require "cli/parser"
 require "cmd/postinstall"
 
 begin
-  args = Homebrew.postinstall_args.parse
+  args = Homebrew::Cmd::Postinstall.new.args
   error_pipe = UNIXSocket.open(ENV.fetch("HOMEBREW_ERROR_PIPE"), &:recv_io)
   error_pipe.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
 
   trap("INT", old_trap)
 
-  formula = args.named.to_resolved_formulae.first
+  formula = T.must(args.named.to_resolved_formulae.first)
   if args.debug?
     require "debrew"
     formula.extend(Debrew::Formula)
diff --git a/Library/Homebrew/test/cmd/postinstall_spec.rb b/Library/Homebrew/test/cmd/postinstall_spec.rb
index 30a7911c22..4acab78340 100644
--- a/Library/Homebrew/test/cmd/postinstall_spec.rb
+++ b/Library/Homebrew/test/cmd/postinstall_spec.rb
@@ -1,7 +1,8 @@
 # frozen_string_literal: true
 
+require "cmd/postinstall"
 require "cmd/shared_examples/args_parse"
 
-RSpec.describe "brew postinstall" do
+RSpec.describe Homebrew::Cmd::Postinstall do
   it_behaves_like "parseable arguments"
 end