diff --git a/Library/Homebrew/cask/audit.rb b/Library/Homebrew/cask/audit.rb
index 1d6fa742e4df8..2c935ae351bb5 100644
--- a/Library/Homebrew/cask/audit.rb
+++ b/Library/Homebrew/cask/audit.rb
@@ -754,7 +754,7 @@ def cask_plist_min_os
     def audit_github_prerelease_version
       odebug "Auditing GitHub prerelease"
       user, repo = get_repo_data(%r{https?://github\.com/([^/]+)/([^/]+)/?.*}) if online?
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       tag = SharedAudits.github_tag_from_url(cask.url)
       tag ||= cask.version
@@ -765,7 +765,7 @@ def audit_github_prerelease_version
     sig { void }
     def audit_gitlab_prerelease_version
       user, repo = get_repo_data(%r{https?://gitlab\.com/([^/]+)/([^/]+)/?.*}) if online?
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       odebug "Auditing GitLab prerelease"
 
@@ -781,7 +781,7 @@ def audit_github_repository_archived
       return if cask.deprecated? || cask.disabled?
 
       user, repo = get_repo_data(%r{https?://github\.com/([^/]+)/([^/]+)/?.*}) if online?
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       metadata = SharedAudits.github_repo_data(user, repo)
       return if metadata.nil?
@@ -795,7 +795,7 @@ def audit_gitlab_repository_archived
       return if cask.deprecated? || cask.disabled?
 
       user, repo = get_repo_data(%r{https?://gitlab\.com/([^/]+)/([^/]+)/?.*}) if online?
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       odebug "Auditing GitLab repo archived"
 
@@ -810,7 +810,7 @@ def audit_github_repository
       return unless new_cask?
 
       user, repo = get_repo_data(%r{https?://github\.com/([^/]+)/([^/]+)/?.*})
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       odebug "Auditing GitHub repo"
 
@@ -823,7 +823,7 @@ def audit_gitlab_repository
       return unless new_cask?
 
       user, repo = get_repo_data(%r{https?://gitlab\.com/([^/]+)/([^/]+)/?.*})
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       odebug "Auditing GitLab repo"
 
@@ -836,7 +836,7 @@ def audit_bitbucket_repository
       return unless new_cask?
 
       user, repo = get_repo_data(%r{https?://bitbucket\.org/([^/]+)/([^/]+)/?.*})
-      return if user.nil?
+      return if user.nil? || repo.nil?
 
       odebug "Auditing Bitbucket repo"
 
diff --git a/Library/Homebrew/extend/os/mac/utils/bottles.rb b/Library/Homebrew/extend/os/mac/utils/bottles.rb
index a06d0db5da9ca..754aeaec64ef7 100644
--- a/Library/Homebrew/extend/os/mac/utils/bottles.rb
+++ b/Library/Homebrew/extend/os/mac/utils/bottles.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 module Utils
@@ -21,6 +21,7 @@ class Collector
 
       alias generic_find_matching_tag find_matching_tag
 
+      sig { params(tag: Utils::Bottles::Tag, no_older_versions: T::Boolean).returns(T.nilable(Utils::Bottles::Tag)) }
       def find_matching_tag(tag, no_older_versions: false)
         # Used primarily by developers testing beta macOS releases.
         if no_older_versions ||
@@ -35,6 +36,7 @@ def find_matching_tag(tag, no_older_versions: false)
       end
 
       # Find a bottle built for a previous version of macOS.
+      sig { params(tag: Utils::Bottles::Tag).returns(T.nilable(Utils::Bottles::Tag)) }
       def find_older_compatible_tag(tag)
         tag_version = begin
           tag.to_macos_version
diff --git a/Library/Homebrew/formula_auditor.rb b/Library/Homebrew/formula_auditor.rb
index f0c63a2e51426..3323313936dac 100644
--- a/Library/Homebrew/formula_auditor.rb
+++ b/Library/Homebrew/formula_auditor.rb
@@ -582,15 +582,13 @@ def audit_eol
       metadata = SharedAudits.eol_data(name, formula.version.major)
       metadata ||= SharedAudits.eol_data(name, formula.version.major_minor)
 
-      return if metadata.blank? || metadata["eol"] == false
+      return if metadata.blank? || (eol_date = metadata["eol"]).blank?
 
-      see_url = "see #{Formatter.url("https://endoflife.date/#{name}")}"
-      if metadata["eol"] == true
-        problem "Product is EOL, #{see_url}"
-        return
-      end
+      message = "Product is EOL"
+      message += " since #{eol_date}" if Date.parse(eol_date.to_s) <= Date.today
+      message += ", see #{Formatter.url("https://endoflife.date/#{name}")}"
 
-      problem "Product is EOL since #{metadata["eol"]}, #{see_url}" if Date.parse(metadata["eol"]) <= Date.today
+      problem message
     end
 
     def audit_wayback_url
@@ -778,8 +776,8 @@ def audit_specs
         problem "#{stable.version} is a development release"
 
       when %r{https?://gitlab\.com/([\w-]+)/([\w-]+)}
-        owner = Regexp.last_match(1)
-        repo = Regexp.last_match(2)
+        owner = T.must(Regexp.last_match(1))
+        repo = T.must(Regexp.last_match(2))
 
         tag = SharedAudits.gitlab_tag_from_url(url)
         tag ||= stable.specs[:tag]
@@ -790,8 +788,8 @@ def audit_specs
           problem error if error
         end
       when %r{^https://github.com/([\w-]+)/([\w-]+)}
-        owner = Regexp.last_match(1)
-        repo = Regexp.last_match(2)
+        owner = T.must(Regexp.last_match(1))
+        repo = T.must(Regexp.last_match(2))
         tag = SharedAudits.github_tag_from_url(url)
         tag ||= formula.stable.specs[:tag]
 
diff --git a/Library/Homebrew/metafiles.rb b/Library/Homebrew/metafiles.rb
index 9f3a74239f401..a321874cf2007 100644
--- a/Library/Homebrew/metafiles.rb
+++ b/Library/Homebrew/metafiles.rb
@@ -1,27 +1,33 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 # Helper for checking if a file is considered a metadata file.
 module Metafiles
-  LICENSES = Set.new(%w[copying copyright license licence]).freeze
+  LICENSES = T.let(Set.new(%w[copying copyright license licence]).freeze, T::Set[String])
   # {https://github.com/github/markup#markups}
-  EXTENSIONS = Set.new(%w[
+  EXTENSIONS = T.let(Set.new(%w[
     .adoc .asc .asciidoc .creole .html .markdown .md .mdown .mediawiki .mkdn
     .org .pod .rdoc .rst .rtf .textile .txt .wiki
-  ]).freeze
-  BASENAMES = Set.new(%w[about authors changelog changes history news notes notice readme todo]).freeze
+  ]).freeze, T::Set[String])
+  BASENAMES = T.let(Set.new(%w[
+    about authors changelog changes history news notes notice readme todo
+  ]).freeze, T::Set[String])
 
   module_function
 
+  sig { params(file: String).returns(T::Boolean) }
   def list?(file)
     return false if %w[.DS_Store INSTALL_RECEIPT.json].include?(file)
 
     !copy?(file)
   end
 
+  sig { params(file: String).returns(T::Boolean) }
   def copy?(file)
     file = file.downcase
-    return true if LICENSES.include? file.split(/\.|-/).first
+    license = file.split(/\.|-/).first
+    return false unless license
+    return true if LICENSES.include?(license)
 
     ext  = File.extname(file)
     file = File.basename(file, ext) if EXTENSIONS.include?(ext)
diff --git a/Library/Homebrew/missing_formula.rb b/Library/Homebrew/missing_formula.rb
index 7a49643accd2c..4b9dbdaee4309 100644
--- a/Library/Homebrew/missing_formula.rb
+++ b/Library/Homebrew/missing_formula.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "formulary"
@@ -7,11 +7,13 @@ module Homebrew
   # Helper module for checking if there is a reason a formula is missing.
   module MissingFormula
     class << self
+      sig { params(name: String, silent: T::Boolean, show_info: T::Boolean).returns(T.nilable(String)) }
       def reason(name, silent: false, show_info: false)
         cask_reason(name, silent:, show_info:) || disallowed_reason(name) ||
           tap_migration_reason(name) || deleted_reason(name, silent:)
       end
 
+      sig { params(name: String).returns(T.nilable(String)) }
       def disallowed_reason(name)
         case name.downcase
         when "gem", /^rubygems?$/ then <<~EOS
@@ -93,6 +95,7 @@ def disallowed_reason(name)
       end
       alias generic_disallowed_reason disallowed_reason
 
+      sig { params(name: String).returns(T.nilable(String)) }
       def tap_migration_reason(name)
         message = T.let(nil, T.nilable(String))
 
@@ -127,6 +130,7 @@ def tap_migration_reason(name)
         message
       end
 
+      sig { params(name: String, silent: T::Boolean).returns(T.nilable(String)) }
       def deleted_reason(name, silent: false)
         path = Formulary.path name
         return if File.exist? path
diff --git a/Library/Homebrew/readall.rb b/Library/Homebrew/readall.rb
index c20251fbb1811..8966214a5cf0c 100644
--- a/Library/Homebrew/readall.rb
+++ b/Library/Homebrew/readall.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "formula"
@@ -16,6 +16,7 @@ module Readall
 
   private_class_method :cache
 
+  sig { params(ruby_files: T::Array[Pathname]).returns(T::Boolean) }
   def self.valid_ruby_syntax?(ruby_files)
     failed = T.let(false, T::Boolean)
     ruby_files.each do |ruby_file|
@@ -25,6 +26,7 @@ def self.valid_ruby_syntax?(ruby_files)
     !failed
   end
 
+  sig { params(alias_dir: Pathname, formula_dir: Pathname).returns(T::Boolean) }
   def self.valid_aliases?(alias_dir, formula_dir)
     return true unless alias_dir.directory?
 
@@ -46,6 +48,7 @@ def self.valid_aliases?(alias_dir, formula_dir)
     !failed
   end
 
+  sig { params(tap: Tap, bottle_tag: T.nilable(Utils::Bottles::Tag)).returns(T::Boolean) }
   def self.valid_formulae?(tap, bottle_tag: nil)
     cache[:valid_formulae] ||= {}
 
@@ -55,7 +58,7 @@ def self.valid_formulae?(tap, bottle_tag: nil)
       next if valid == true || valid&.include?(bottle_tag)
 
       formula_name = file.basename(".rb").to_s
-      formula_contents = file.read(encoding: "UTF-8")
+      formula_contents = file.read.force_encoding("UTF-8")
 
       readall_namespace = "ReadallNamespace"
       readall_formula_class = Formulary.load_formula(formula_name, file, formula_contents, readall_namespace,
@@ -79,10 +82,16 @@ def self.valid_formulae?(tap, bottle_tag: nil)
     success
   end
 
+  sig { params(_tap: Tap, os_name: T.nilable(Symbol), arch: T.nilable(Symbol)).returns(T::Boolean) }
   def self.valid_casks?(_tap, os_name: nil, arch: nil)
     true
   end
 
+  sig {
+    params(
+      tap: Tap, aliases: T::Boolean, no_simulate: T::Boolean, os_arch_combinations: T::Array[T::Array[String]],
+    ).returns(T::Boolean)
+  }
   def self.valid_tap?(tap, aliases: false, no_simulate: false,
                       os_arch_combinations: OnSystem::ALL_OS_ARCH_COMBINATIONS)
     success = true
@@ -110,6 +119,7 @@ def self.valid_tap?(tap, aliases: false, no_simulate: false,
     success
   end
 
+  sig { params(filename: Pathname).returns(T::Boolean) }
   private_class_method def self.syntax_errors_or_warnings?(filename)
     # Retrieve messages about syntax errors/warnings printed to `$stderr`.
     _, err, status = system_command(RUBY_PATH, args: ["-c", "-w", filename], print_stderr: false)
diff --git a/Library/Homebrew/unlink.rb b/Library/Homebrew/unlink.rb
index 73ce64081690d..228cd8736cc27 100644
--- a/Library/Homebrew/unlink.rb
+++ b/Library/Homebrew/unlink.rb
@@ -1,9 +1,10 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 module Homebrew
   # Provides helper methods for unlinking formulae and kegs with consistent output.
   module Unlink
+    sig { params(formula: Formula, verbose: T::Boolean).void }
     def self.unlink_versioned_formulae(formula, verbose: false)
       formula.versioned_formulae
              .select(&:keg_only?)
@@ -15,6 +16,7 @@ def self.unlink_versioned_formulae(formula, verbose: false)
       end
     end
 
+    sig { params(keg: Keg, dry_run: T::Boolean, verbose: T::Boolean).void }
     def self.unlink(keg, dry_run: false, verbose: false)
       options = { dry_run:, verbose: }
 
diff --git a/Library/Homebrew/utils/link.rb b/Library/Homebrew/utils/link.rb
index 09e56d2696cf7..01a5211b3ec7a 100644
--- a/Library/Homebrew/utils/link.rb
+++ b/Library/Homebrew/utils/link.rb
@@ -1,9 +1,10 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 module Utils
   # Helper functions for creating symlinks.
   module Link
+    sig { params(src_dir: Pathname, dst_dir: Pathname, command: String, link_dir: T::Boolean).void }
     def self.link_src_dst_dirs(src_dir, dst_dir, command, link_dir: false)
       return unless src_dir.exist?
 
@@ -38,6 +39,7 @@ def self.link_src_dst_dirs(src_dir, dst_dir, command, link_dir: false)
     end
     private_class_method :link_src_dst_dirs
 
+    sig { params(src_dir: Pathname, dst_dir: Pathname, unlink_dir: T::Boolean).void }
     def self.unlink_src_dst_dirs(src_dir, dst_dir, unlink_dir: false)
       return unless src_dir.exist?
 
@@ -52,26 +54,31 @@ def self.unlink_src_dst_dirs(src_dir, dst_dir, unlink_dir: false)
     end
     private_class_method :unlink_src_dst_dirs
 
+    sig { params(path: Pathname, command: String).void }
     def self.link_manpages(path, command)
       link_src_dst_dirs(path/"manpages", HOMEBREW_PREFIX/"share/man/man1", command)
     end
 
+    sig { params(path: Pathname).void }
     def self.unlink_manpages(path)
       unlink_src_dst_dirs(path/"manpages", HOMEBREW_PREFIX/"share/man/man1")
     end
 
+    sig { params(path: Pathname, command: String).void }
     def self.link_completions(path, command)
       link_src_dst_dirs(path/"completions/bash", HOMEBREW_PREFIX/"etc/bash_completion.d", command)
       link_src_dst_dirs(path/"completions/zsh", HOMEBREW_PREFIX/"share/zsh/site-functions", command)
       link_src_dst_dirs(path/"completions/fish", HOMEBREW_PREFIX/"share/fish/vendor_completions.d", command)
     end
 
+    sig { params(path: Pathname).void }
     def self.unlink_completions(path)
       unlink_src_dst_dirs(path/"completions/bash", HOMEBREW_PREFIX/"etc/bash_completion.d")
       unlink_src_dst_dirs(path/"completions/zsh", HOMEBREW_PREFIX/"share/zsh/site-functions")
       unlink_src_dst_dirs(path/"completions/fish", HOMEBREW_PREFIX/"share/fish/vendor_completions.d")
     end
 
+    sig { params(path: Pathname, command: String).void }
     def self.link_docs(path, command)
       link_src_dst_dirs(path/"docs", HOMEBREW_PREFIX/"share/doc/homebrew", command, link_dir: true)
     end
diff --git a/Library/Homebrew/utils/service.rb b/Library/Homebrew/utils/service.rb
index ceb8cd36e2bf2..3c13d75c70ce0 100644
--- a/Library/Homebrew/utils/service.rb
+++ b/Library/Homebrew/utils/service.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 module Utils
@@ -27,7 +27,7 @@ def self.launchctl
       return @launchctl if defined? @launchctl
       return if ENV["HOMEBREW_TEST_GENERIC_OS"]
 
-      @launchctl = which("launchctl")
+      @launchctl = T.let(which("launchctl"), T.nilable(Pathname))
     end
 
     # Path to systemctl binary.
@@ -36,7 +36,7 @@ def self.systemctl
       return @systemctl if defined? @systemctl
       return if ENV["HOMEBREW_TEST_GENERIC_OS"]
 
-      @systemctl = which("systemctl")
+      @systemctl = T.let(which("systemctl"), T.nilable(Pathname))
     end
 
     sig { returns(T::Boolean) }
diff --git a/Library/Homebrew/utils/shared_audits.rb b/Library/Homebrew/utils/shared_audits.rb
index 3329ea1797fb4..b7cd07a4c496d 100644
--- a/Library/Homebrew/utils/shared_audits.rb
+++ b/Library/Homebrew/utils/shared_audits.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "utils/curl"
@@ -10,8 +10,9 @@ module SharedAudits
 
   module_function
 
+  sig { params(product: String, cycle: String).returns(T.nilable(T::Hash[String, T::Hash[Symbol, T.untyped]])) }
   def eol_data(product, cycle)
-    @eol_data ||= {}
+    @eol_data ||= T.let({}, T.nilable(T::Hash[String, T::Hash[String, T.untyped]]))
     @eol_data["#{product}/#{cycle}"] ||= begin
       out, _, status = Utils::Curl.curl_output("--location", "https://endoflife.date/api/#{product}/#{cycle}.json")
       json = JSON.parse(out) if status.success?
@@ -20,8 +21,9 @@ def eol_data(product, cycle)
     end
   end
 
+  sig { params(user: String, repo: String).returns(T.nilable(T::Hash[String, T.untyped])) }
   def github_repo_data(user, repo)
-    @github_repo_data ||= {}
+    @github_repo_data ||= T.let({}, T.nilable(T::Hash[String, T.untyped]))
     @github_repo_data["#{user}/#{repo}"] ||= GitHub.repository(user, repo)
 
     @github_repo_data["#{user}/#{repo}"]
@@ -31,10 +33,11 @@ def github_repo_data(user, repo)
     raise unless e.message.match?(GitHub::API::GITHUB_IP_ALLOWLIST_ERROR)
   end
 
+  sig { params(user: String, repo: String, tag: String).returns(T.nilable(T::Hash[String, T.untyped])) }
   def github_release_data(user, repo, tag)
     id = "#{user}/#{repo}/#{tag}"
     url = "#{GitHub::API_URL}/repos/#{user}/#{repo}/releases/tags/#{tag}"
-    @github_release_data ||= {}
+    @github_release_data ||= T.let({}, T.nilable(T::Hash[String, T.untyped]))
     @github_release_data[id] ||= GitHub::API.open_rest(url)
 
     @github_release_data[id]
@@ -44,6 +47,13 @@ def github_release_data(user, repo, tag)
     raise unless e.message.match?(GitHub::API::GITHUB_IP_ALLOWLIST_ERROR)
   end
 
+  sig {
+    params(
+      user: String, repo: String, tag: String, formula: T.nilable(Formula), cask: T.nilable(Cask::Cask),
+    ).returns(
+      T.nilable(String),
+    )
+  }
   def github_release(user, repo, tag, formula: nil, cask: nil)
     release = github_release_data(user, repo, tag)
     return unless release
@@ -63,8 +73,9 @@ def github_release(user, repo, tag, formula: nil, cask: nil)
     "#{tag} is a GitHub draft." if release["draft"]
   end
 
+  sig { params(user: String, repo: String).returns(T.nilable(T::Hash[String, T.untyped])) }
   def gitlab_repo_data(user, repo)
-    @gitlab_repo_data ||= {}
+    @gitlab_repo_data ||= T.let({}, T.nilable(T::Hash[String, T.untyped]))
     @gitlab_repo_data["#{user}/#{repo}"] ||= begin
       out, _, status = Utils::Curl.curl_output("https://gitlab.com/api/v4/projects/#{user}%2F#{repo}")
       json = JSON.parse(out) if status.success?
@@ -73,9 +84,10 @@ def gitlab_repo_data(user, repo)
     end
   end
 
+  sig { params(user: String, repo: String, tag: String).returns(T.nilable(T::Hash[String, T.untyped])) }
   def gitlab_release_data(user, repo, tag)
     id = "#{user}/#{repo}/#{tag}"
-    @gitlab_release_data ||= {}
+    @gitlab_release_data ||= T.let({}, T.nilable(T::Hash[String, T.untyped]))
     @gitlab_release_data[id] ||= begin
       out, _, status = Utils::Curl.curl_output(
         "https://gitlab.com/api/v4/projects/#{user}%2F#{repo}/releases/#{tag}", "--fail"
@@ -84,6 +96,13 @@ def gitlab_release_data(user, repo, tag)
     end
   end
 
+  sig {
+    params(
+      user: String, repo: String, tag: String, formula: T.nilable(Formula), cask: T.nilable(Cask::Cask),
+    ).returns(
+      T.nilable(String),
+    )
+  }
   def gitlab_release(user, repo, tag, formula: nil, cask: nil)
     release = gitlab_release_data(user, repo, tag)
     return unless release
@@ -100,6 +119,7 @@ def gitlab_release(user, repo, tag, formula: nil, cask: nil)
     "#{tag} is a GitLab pre-release."
   end
 
+  sig { params(user: String, repo: String).returns(T.nilable(String)) }
   def github(user, repo)
     metadata = github_repo_data(user, repo)
 
@@ -117,6 +137,7 @@ def github(user, repo)
     "GitHub repository too new (<30 days old)"
   end
 
+  sig { params(user: String, repo: String).returns(T.nilable(String)) }
   def gitlab(user, repo)
     metadata = gitlab_repo_data(user, repo)
 
@@ -132,6 +153,7 @@ def gitlab(user, repo)
     "GitLab repository too new (<30 days old)"
   end
 
+  sig { params(user: String, repo: String).returns(T.nilable(String)) }
   def bitbucket(user, repo)
     api_url = "https://api.bitbucket.org/2.0/repositories/#{user}/#{repo}"
     out, _, status = Utils::Curl.curl_output("--request", "GET", api_url)
@@ -163,6 +185,7 @@ def bitbucket(user, repo)
     "Bitbucket repository not notable enough (<30 forks and <75 watchers)"
   end
 
+  sig { params(url: String).returns(T.nilable(String)) }
   def github_tag_from_url(url)
     url = url.to_s
     tag = url.match(%r{^https://github\.com/[\w-]+/[\w-]+/archive/refs/tags/([^/]+)\.(tar\.gz|zip)$})
@@ -174,6 +197,7 @@ def github_tag_from_url(url)
     tag
   end
 
+  sig { params(url: String).returns(T.nilable(String)) }
   def gitlab_tag_from_url(url)
     url = url.to_s
     url.match(%r{^https://gitlab\.com/[\w-]+/[\w-]+/-/archive/([^/]+)/})
diff --git a/Library/Homebrew/utils/svn.rb b/Library/Homebrew/utils/svn.rb
index 93f6b100a976d..049e95e7985b5 100644
--- a/Library/Homebrew/utils/svn.rb
+++ b/Library/Homebrew/utils/svn.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "system_command"
@@ -19,7 +19,7 @@ def version
         return @version if defined?(@version)
 
         stdout, _, status = system_command(HOMEBREW_SHIMS_PATH/"shared/svn", args: ["--version"], print_stderr: false)
-        @version = status.success? ? stdout.chomp[/svn, version (\d+(?:\.\d+)*)/, 1] : nil
+        @version = T.let(status.success? ? stdout.chomp[/svn, version (\d+(?:\.\d+)*)/, 1] : nil, T.nilable(String))
       end
 
       sig { params(url: String).returns(T::Boolean) }
@@ -34,7 +34,7 @@ def remote_exists?(url)
         system_command("svn", args: args.concat(invalid_cert_flags), print_stderr: false).success?
       end
 
-      sig { returns(Array) }
+      sig { returns(T::Array[String]) }
       def invalid_cert_flags
         opoo "Ignoring Subversion certificate errors!"
         args = ["--non-interactive", "--trust-server-cert"]
@@ -44,6 +44,7 @@ def invalid_cert_flags
         args
       end
 
+      sig { void }
       def clear_version_cache
         remove_instance_variable(:@version) if defined?(@version)
       end
diff --git a/Library/Homebrew/utils/user.rb b/Library/Homebrew/utils/user.rb
index 09be3d770774e..72339509f6860 100644
--- a/Library/Homebrew/utils/user.rb
+++ b/Library/Homebrew/utils/user.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "delegate"
@@ -29,6 +29,6 @@ def self.current
     pwuid = Etc.getpwuid(Process.euid)
     return if pwuid.nil?
 
-    @current = new(pwuid.name)
+    @current = T.let(new(pwuid.name), T.nilable(T.attached_class))
   end
 end