diff --git a/Library/Homebrew/extend/on_system.rbi b/Library/Homebrew/extend/on_system.rbi
index 15534bb4b4..c80492017b 100644
--- a/Library/Homebrew/extend/on_system.rbi
+++ b/Library/Homebrew/extend/on_system.rbi
@@ -4,3 +4,20 @@ module OnSystem::MacOSOnly
   sig { params(arm: T.nilable(String), intel: T.nilable(String)).returns(T.nilable(String)) }
   def on_arch_conditional(arm: nil, intel: nil); end
 end
+
+module OnSystem::MacOSAndLinux
+  sig {
+    params(
+      macos: T.nilable(T.any(T::Array[T.any(String, Pathname)], String, Pathname)),
+      linux: T.nilable(T.any(T::Array[T.any(String, Pathname)], String, Pathname)),
+    ).returns(T.nilable(T.any(T::Array[T.any(String, Pathname)], String, Pathname)))
+  }
+  def on_system_conditional(macos: nil, linux: nil); end
+
+  sig {
+    type_parameters(:U)
+      .params(block: T.proc.returns(T.type_parameter(:U)))
+      .returns(T.type_parameter(:U))
+  }
+  def on_macos(&block); end
+end
diff --git a/Library/Homebrew/formula.rbi b/Library/Homebrew/formula.rbi
deleted file mode 100644
index 2beea9c311..0000000000
--- a/Library/Homebrew/formula.rbi
+++ /dev/null
@@ -1,6 +0,0 @@
-# typed: strict
-
-class Formula
-  # This method is included by `OnSystem`
-  def self.on_macos(&block); end
-end
diff --git a/Library/Homebrew/service.rbi b/Library/Homebrew/service.rbi
deleted file mode 100644
index 5777dab11b..0000000000
--- a/Library/Homebrew/service.rbi
+++ /dev/null
@@ -1,7 +0,0 @@
-# typed: strict
-
-module Homebrew
-  class Service
-    def on_system_conditional(macos: nil, linux: nil); end
-  end
-end
diff --git a/Library/Homebrew/utils/gems.rbi b/Library/Homebrew/utils/gems.rbi
deleted file mode 100644
index 746bceef1d..0000000000
--- a/Library/Homebrew/utils/gems.rbi
+++ /dev/null
@@ -1,27 +0,0 @@
-# typed: strict
-
-module Homebrew
-  sig { returns(String) }
-  def ruby_bindir; end
-
-  sig { returns(String) }
-  def gem_user_bindir; end
-
-  sig { params(message: String).void }
-  def ohai_if_defined(message); end
-
-  sig { params(message: String).returns(T.noreturn) }
-  def odie_if_defined(message); end
-
-  sig { params(name: String, version: T.nilable(String), executable: String, setup_gem_environment: T::Boolean).void }
-  def install_gem_setup_path!(name, version: nil, executable: name, setup_gem_environment: true); end
-
-  sig { params(executable: String).returns(T.nilable(String)) }
-  def find_in_path(executable); end
-
-  sig { void }
-  def install_bundler!; end
-
-  sig { params(only_warn_on_failure: T::Boolean, setup_path: T::Boolean, groups: T::Array[String]).void }
-  def install_bundler_gems!(only_warn_on_failure: false, setup_path: false, groups: []); end
-end