diff --git a/Library/Homebrew/cmd/untap.rb b/Library/Homebrew/cmd/untap.rb
index 17c5c11af6..fdac754001 100644
--- a/Library/Homebrew/cmd/untap.rb
+++ b/Library/Homebrew/cmd/untap.rb
@@ -49,7 +49,7 @@ module Homebrew
       sig { params(tap: Tap).returns(T::Array[Formula]) }
       def installed_formulae_for(tap:)
         tap.formula_names.filter_map do |formula_name|
-          next unless installed_formulae_names.include?(T.must(formula_name.split("/").last))
+          next unless installed_formulae_names.include?(formula_name.split("/").fetch(-1))
 
           formula = begin
             Formulary.factory(formula_name)
@@ -68,7 +68,7 @@ module Homebrew
       sig { params(tap: Tap).returns(T::Array[Cask::Cask]) }
       def installed_casks_for(tap:)
         tap.cask_tokens.filter_map do |cask_token|
-          next unless installed_cask_tokens.include?(T.must(cask_token.split("/").last))
+          next unless installed_cask_tokens.include?(cask_token.split("/").fetch(-1))
 
           cask = begin
             Cask::CaskLoader.load(cask_token)
diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index 70ec32074c..13bed07d10 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -500,7 +500,7 @@ class Reporter
       case status
       when "A", "D"
         full_name = tap.formula_file_to_name(src)
-        name = T.must(full_name.split("/").last)
+        name = full_name.split("/").fetch(-1)
         new_tap = tap.tap_migrations[name]
         @report[T.must(status).to_sym] << full_name unless new_tap
       when "M"
@@ -614,7 +614,7 @@ class Reporter
   sig { void }
   def migrate_tap_migration
     (Array(report[:D]) + Array(report[:DC])).each do |full_name|
-      name = T.must(full_name.split("/").last)
+      name = full_name.split("/").fetch(-1)
       new_tap_name = tap.tap_migrations[name]
       next if new_tap_name.nil? # skip if not in tap_migrations list.
 
@@ -901,7 +901,7 @@ class ReporterHub
       true
     end
     casks.each do |cask|
-      cask_token = T.must(cask.split("/").last)
+      cask_token = cask.split("/").fetch(-1)
       if should_display_descriptions && (desc = cask_description(cask))
         puts "#{cask_token}: #{desc}"
       else
@@ -924,7 +924,7 @@ class ReporterHub
     return if Homebrew::SimulateSystem.simulating_or_running_on_linux?
 
     casks = select_formula_or_cask(:DC).sort.filter_map do |name|
-      name = T.must(name.split("/").last)
+      name = name.split("/").fetch(-1)
       pretty_uninstalled(name) if cask_installed?(name)
     end
 
diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index 4c4235d38d..e76fa53e3f 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -1332,7 +1332,7 @@ module Formulary
     if (possible_alias = tap.alias_table[alias_table_key].presence)
       # FIXME: Remove the need to split the name and instead make
       #        the alias table only contain short names.
-      name = T.must(possible_alias.split("/").last)
+      name = possible_alias.split("/").fetch(-1)
       type = :alias
     elsif (new_name = tap.formula_renames[name].presence)
       old_name = tap.core_tap? ? name : tapped_name