diff --git a/Library/Homebrew/cli/args.rbi b/Library/Homebrew/cli/args.rbi
index b719d78fa4..51e9ccadb9 100644
--- a/Library/Homebrew/cli/args.rbi
+++ b/Library/Homebrew/cli/args.rbi
@@ -65,6 +65,9 @@ module Homebrew
 
       sig { returns(T.nilable(T::Boolean)) }
       def ignore_dependencies?; end
+
+      sig { returns(T.nilable(T::Boolean)) }
+      def keep_tmp?; end
     end
   end
 end
diff --git a/Library/Homebrew/test.rb b/Library/Homebrew/test.rb
index 9e01cf13a7..6ef080962d 100644
--- a/Library/Homebrew/test.rb
+++ b/Library/Homebrew/test.rb
@@ -30,13 +30,13 @@ begin
     raise "cannot kill child processes without `pkill`, please install!" unless which("pkill")
   end
 
-  formula = args.named.to_resolved_formulae.first
+  formula = T.must(args.named.to_resolved_formulae.first)
   formula.extend(Homebrew::Assertions)
   formula.extend(Homebrew::FreePort)
   formula.extend(Debrew::Formula) if args.debug?
 
   ENV.extend(Stdenv)
-  ENV.setup_build_environment(formula: formula)
+  T.cast(ENV, Stdenv).setup_build_environment(formula: formula)
 
   # tests can also return false to indicate failure
   Timeout.timeout TEST_TIMEOUT_SECONDS do