diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index 4df272dd3f..41e67f8c9f 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -130,7 +130,7 @@ module Homebrew
 
       new_tag = Utils.popen_read(
         "git", "-C", HOMEBREW_REPOSITORY, "tag", "--list", "--sort=-version:refname", "*.*"
-      ).lines.fetch(0).chomp
+      ).lines.first.chomp
 
       Settings.write "latesttag", new_tag if new_tag != old_tag
 
@@ -286,8 +286,6 @@ module Homebrew
     puts
 
     new_major_version, new_minor_version, new_patch_version = new_tag.split(".").map(&:to_i)
-    raise "Invalid new tag: #{new_tag}" if !new_major_version || !new_minor_version || !new_patch_version
-
     old_major_version, old_minor_version = (old_tag.split(".")[0, 2]).map(&:to_i) if old_tag.present?
     if old_tag.blank? || new_major_version > old_major_version \
         || new_minor_version > old_minor_version
diff --git a/Library/Homebrew/dev-cmd/pr-pull.rb b/Library/Homebrew/dev-cmd/pr-pull.rb
index 2b6ceafab3..f37f993463 100644
--- a/Library/Homebrew/dev-cmd/pr-pull.rb
+++ b/Library/Homebrew/dev-cmd/pr-pull.rb
@@ -234,13 +234,13 @@ module Homebrew
                                     "--reverse", "#{original_commit}..HEAD").lines.map(&:strip)
 
     # Generate a bidirectional mapping of commits <=> formula/cask files.
-    files_to_commits = T.let({}, T::Hash[String, T::Array[String]])
+    files_to_commits = {}
     commits_to_files = commits.to_h do |commit|
       files = Utils.safe_popen_read("git", "-C", tap.path, "diff-tree", "--diff-filter=AMD",
                                     "-r", "--name-only", "#{commit}^", commit).lines.map(&:strip)
       files.each do |file|
         files_to_commits[file] ||= []
-        files_to_commits.fetch(file) << commit
+        files_to_commits[file] << commit
         tap_file = tap.path/file
         if (tap_file.dirname == tap.formula_dir || tap_file.dirname == tap.cask_dir) &&
            File.extname(file) == ".rb"
@@ -266,14 +266,14 @@ module Homebrew
       next if processed_commits.include? commit
 
       files = commits_to_files[commit]
-      if files.length == 1 && files_to_commits.fetch(files.first).length == 1
+      if files.length == 1 && files_to_commits[files.first].length == 1
         # If there's a 1:1 mapping of commits to files, just cherry pick and (maybe) reword.
         reword_package_commit(commit, files.first, path: tap.path, reason: reason, verbose: verbose, resolve: resolve)
         processed_commits << commit
-      elsif files.length == 1 && files_to_commits.fetch(files.first).length > 1
+      elsif files.length == 1 && files_to_commits[files.first].length > 1
         # If multiple commits modify a single file, squash them down into a single commit.
         file = files.first
-        commits = files_to_commits.fetch(file)
+        commits = files_to_commits[file]
         squash_package_commits(commits, file, path: tap.path, reason: reason, verbose: verbose, resolve: resolve)
         processed_commits += commits
       else
@@ -336,7 +336,7 @@ module Homebrew
       rescue FormulaUnavailableError
         nil
       end
-    end
+    end.compact
     casks = Utils.popen_read("git", "-C", tap.path, "diff-tree",
                              "-r", "--name-only", "--diff-filter=AM",
                              original_commit, "HEAD", "--", tap.cask_dir)
@@ -351,7 +351,7 @@ module Homebrew
         nil
       end
     end.compact
-    T.must(formulae).compact + casks
+    formulae + casks
   end
 
   def self.download_artifact(url, dir, pull_request)
diff --git a/Library/Homebrew/extend/os/linux/extend/ENV/super.rb b/Library/Homebrew/extend/os/linux/extend/ENV/super.rb
index f4288627f3..c0691c0001 100644
--- a/Library/Homebrew/extend/os/linux/extend/ENV/super.rb
+++ b/Library/Homebrew/extend/os/linux/extend/ENV/super.rb
@@ -40,11 +40,8 @@ module Superenv
     paths = []
     # Add paths for GCC headers when building against glibc@2.13 because we have to use -nostdinc.
     if deps.any? { |d| d.name == "glibc@2.13" }
-      env_cc = cc
-      raise "No CC compiler found in ENV" if env_cc.nil?
-
-      gcc_include_dir = Utils.safe_popen_read(env_cc, "--print-file-name=include").chomp
-      gcc_include_fixed_dir = Utils.safe_popen_read(env_cc, "--print-file-name=include-fixed").chomp
+      gcc_include_dir = Utils.safe_popen_read(cc, "--print-file-name=include").chomp
+      gcc_include_fixed_dir = Utils.safe_popen_read(cc, "--print-file-name=include-fixed").chomp
       paths << gcc_include_dir << gcc_include_fixed_dir
     end
     paths
diff --git a/Library/Homebrew/keg_relocate.rb b/Library/Homebrew/keg_relocate.rb
index f80d6f867f..083529719b 100644
--- a/Library/Homebrew/keg_relocate.rb
+++ b/Library/Homebrew/keg_relocate.rb
@@ -338,7 +338,7 @@ class Keg
         # Some binaries contain strings with lists of files
         # e.g. `/usr/local/lib/foo:/usr/local/share/foo:/usr/lib/foo`
         # Each item in the list should be checked separately
-        T.must(match).split(":").each do |sub_match|
+        match.split(":").each do |sub_match|
           # Not all items in the list may be matches
           next unless sub_match.match? path_regex
           next if linked_libraries.include? sub_match # Don't bother reporting a string if it was found by otool
diff --git a/Library/Homebrew/language/node.rb b/Library/Homebrew/language/node.rb
index 158a061e05..4421b0f9e8 100644
--- a/Library/Homebrew/language/node.rb
+++ b/Library/Homebrew/language/node.rb
@@ -34,7 +34,7 @@ module Language
       output = Utils.popen_read("npm", "pack", "--ignore-scripts")
       raise "npm failed to pack #{Dir.pwd}" if !$CHILD_STATUS.exitstatus.zero? || output.lines.empty?
 
-      output.lines.fetch(-1).chomp
+      output.lines.last.chomp
     end
 
     def self.setup_npm_environment
diff --git a/Library/Homebrew/missing_formula.rb b/Library/Homebrew/missing_formula.rb
index 1f76c80530..884c3b73fc 100644
--- a/Library/Homebrew/missing_formula.rb
+++ b/Library/Homebrew/missing_formula.rb
@@ -179,7 +179,7 @@ module Homebrew
             return
           end
 
-          commit_message = T.must(commit_message).reject(&:empty?).join("\n  ")
+          commit_message = commit_message.reject(&:empty?).join("\n  ")
 
           commit_message.sub!(/ \(#(\d+)\)$/, " (#{tap.issues_url}/\\1)")
           commit_message.gsub!(/(Closes|Fixes) #(\d+)/, "\\1 #{tap.issues_url}/\\2")
diff --git a/Library/Homebrew/os/linux.rb b/Library/Homebrew/os/linux.rb
index f3bef19f07..2b5df8cfc3 100644
--- a/Library/Homebrew/os/linux.rb
+++ b/Library/Homebrew/os/linux.rb
@@ -14,7 +14,7 @@ module OS
     def os_version
       if which("lsb_release")
         lsb_info = Utils.popen_read("lsb_release", "-a")
-        description = T.must(lsb_info[/^Description:\s*(.*)$/, 1]).force_encoding("UTF-8")
+        description = lsb_info[/^Description:\s*(.*)$/, 1].force_encoding("UTF-8")
         codename = lsb_info[/^Codename:\s*(.*)$/, 1]
         if codename.blank? || (codename == "n/a")
           description
diff --git a/Library/Homebrew/os/linux/elf.rb b/Library/Homebrew/os/linux/elf.rb
index 92212d0d49..ca7d078b89 100644
--- a/Library/Homebrew/os/linux/elf.rb
+++ b/Library/Homebrew/os/linux/elf.rb
@@ -131,7 +131,7 @@ module ELFShim
       return if needed.empty?
 
       ldd = DevelopmentTools.locate "ldd"
-      ldd_output = Utils.popen_read(T.must(ldd), path.expand_path.to_s).split("\n")
+      ldd_output = Utils.popen_read(ldd, path.expand_path.to_s).split("\n")
       return unless $CHILD_STATUS.success?
 
       ldd_paths = ldd_output.map do |line|
diff --git a/Library/Homebrew/os/mac/sdk.rb b/Library/Homebrew/os/mac/sdk.rb
index 734c90c401..3fadf31762 100644
--- a/Library/Homebrew/os/mac/sdk.rb
+++ b/Library/Homebrew/os/mac/sdk.rb
@@ -161,8 +161,7 @@ module OS
           # Xcode.prefix is pretty smart, so let's look inside to find the sdk
           sdk_prefix = "#{Xcode.prefix}/Platforms/MacOSX.platform/Developer/SDKs"
           # Finally query Xcode itself (this is slow, so check it last)
-          sdk_platform_path = Utils.popen_read(T.must(DevelopmentTools.locate("xcrun")),
-                                               "--show-sdk-platform-path").chomp
+          sdk_platform_path = Utils.popen_read(DevelopmentTools.locate("xcrun"), "--show-sdk-platform-path").chomp
           sdk_prefix = File.join(sdk_platform_path, "Developer", "SDKs") unless File.directory? sdk_prefix
 
           sdk_prefix
diff --git a/Library/Homebrew/utils/popen.rb b/Library/Homebrew/utils/popen.rb
index 6dc2ffa920..733923257d 100644
--- a/Library/Homebrew/utils/popen.rb
+++ b/Library/Homebrew/utils/popen.rb
@@ -1,20 +1,10 @@
-# typed: strict
+# typed: true
 # frozen_string_literal: true
 
 module Utils
-  extend T::Sig
-
   IO_DEFAULT_BUFFER_SIZE = 4096
   private_constant :IO_DEFAULT_BUFFER_SIZE
 
-  sig {
-    params(
-      args:    T.any(Pathname, String, T::Hash[String, String]),
-      safe:    T::Boolean,
-      options: T.untyped,
-      block:   T.nilable(T.proc.params(io: IO).void),
-    ).returns(T.nilable(String))
-  }
   def self.popen_read(*args, safe: false, **options, &block)
     output = popen(args, "rb", options, &block)
     return output if !safe || $CHILD_STATUS.success?
@@ -22,26 +12,11 @@ module Utils
     raise ErrorDuringExecution.new(args, status: $CHILD_STATUS, output: [[:stdout, output]])
   end
 
-  sig {
-    params(
-      args:    T.any(Pathname, String, T::Hash[String, String]),
-      options: T.untyped,
-      block:   T.nilable(T.proc.params(io: IO).void),
-    ).returns(T.nilable(String))
-  }
   def self.safe_popen_read(*args, **options, &block)
     popen_read(*args, safe: true, **options, &block)
   end
 
-  sig {
-    params(
-      args:    T.any(Pathname, String, T::Hash[String, String]),
-      safe:    T::Boolean,
-      options: T.untyped,
-      _block:  T.proc.params(io: IO).void,
-    ).returns(T.nilable(String))
-  }
-  def self.popen_write(*args, safe: false, **options, &_block)
+  def self.popen_write(*args, safe: false, **options)
     output = ""
     popen(args, "w+b", options) do |pipe|
       # Before we yield to the block, capture as much output as we can
@@ -56,7 +31,7 @@ module Utils
       pipe.wait_readable
 
       # Capture the rest of the output
-      output += T.must(pipe.read)
+      output += pipe.read
       output.freeze
     end
     return output if !safe || $CHILD_STATUS.success?
@@ -64,29 +39,14 @@ module Utils
     raise ErrorDuringExecution.new(args, status: $CHILD_STATUS, output: [[:stdout, output]])
   end
 
-  sig {
-    params(
-      args:    T.any(Pathname, String, T::Hash[String, String]),
-      options: T.untyped,
-      block:   T.nilable(T.proc.params(io: IO).void),
-    ).returns(T.nilable(String))
-  }
   def self.safe_popen_write(*args, **options, &block)
     popen_write(*args, safe: true, **options, &block)
   end
 
-  sig {
-    params(
-      args:    T::Array[T.any(Pathname, String, T::Hash[String, String])],
-      mode:    String,
-      options: T::Hash[Symbol, T.untyped],
-      block:   T.nilable(T.proc.params(io: IO).void),
-    ).returns(T.nilable(String))
-  }
-  def self.popen(args, mode, options = {}, &block)
+  def self.popen(args, mode, options = {})
     IO.popen("-", mode) do |pipe|
       if pipe
-        return pipe.read unless block
+        return pipe.read unless block_given?
 
         yield pipe
       else