diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index ee2d2b0218..be714073e8 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -654,7 +654,7 @@ class FormulaInstaller
     @show_header = true unless deps.empty?
   end
 
-  sig { params(dep: Formula).void }
+  sig { params(dep: Dependency).void }
   def fetch_dependency(dep)
     df = dep.to_formula
     fi = FormulaInstaller.new(
@@ -675,7 +675,7 @@ class FormulaInstaller
     fi.fetch
   end
 
-  sig { params(dep: Formula, inherited_options: Options).void }
+  sig { params(dep: Dependency, inherited_options: Options).void }
   def install_dependency(dep, inherited_options)
     df = dep.to_formula
     tab = Tab.for_formula(df)
diff --git a/Library/Homebrew/tap_auditor.rb b/Library/Homebrew/tap_auditor.rb
index c38e9abaf6..d8294815f2 100644
--- a/Library/Homebrew/tap_auditor.rb
+++ b/Library/Homebrew/tap_auditor.rb
@@ -10,7 +10,7 @@ module Homebrew
 
     attr_reader :name, :path, :tap_audit_exceptions, :problems
 
-    sig { params(tap: Tap, strict: T::Boolean).void }
+    sig { params(tap: Tap, strict: T.nilable(T::Boolean)).void }
     def initialize(tap, strict:)
       @name                 = tap.name
       @path                 = tap.path