diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 19b3fb31dc00b..d5e23a7d7a3c7 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -77,6 +77,9 @@ class Formula
   extend Cachable
   extend Attrable
   extend APIHashable
+  extend T::Helpers
+
+  abstract!
 
   SUPPORTED_NETWORK_ACCESS_PHASES = [:build, :test, :postinstall].freeze
   private_constant :SUPPORTED_NETWORK_ACCESS_PHASES
@@ -1596,7 +1599,11 @@ def patch
 
   # Yields |self,staging| with current working directory set to the uncompressed tarball
   # where staging is a {Mktemp} staging context.
-  def brew(fetch: true, keep_tmp: false, debug_symbols: false, interactive: false)
+  sig(:final) {
+    params(fetch: T::Boolean, keep_tmp: T::Boolean, debug_symbols: T::Boolean, interactive: T::Boolean,
+           _blk: T.proc.params(arg0: Formula, arg1: Mktemp).void).void
+  }
+  def brew(fetch: true, keep_tmp: false, debug_symbols: false, interactive: false, &_blk)
     @prefix_returns_versioned_prefix = true
     active_spec.fetch if fetch
     stage(interactive:, debug_symbols:) do |staging|
@@ -3346,6 +3353,7 @@ def method_added(method)
 
       case method
       when :brew
+        # This method has a `:final` sig, but we want to enforce it even when the sorbet runtime is disabled.
         raise "You cannot override Formula#brew in class #{name}"
       when :test
         define_method(:test_defined?) { true }
diff --git a/Library/Homebrew/requirement.rb b/Library/Homebrew/requirement.rb
index 9edd6a9a2306c..9a25941df19ba 100644
--- a/Library/Homebrew/requirement.rb
+++ b/Library/Homebrew/requirement.rb
@@ -13,14 +13,15 @@
 class Requirement
   include Dependable
   extend Cachable
+  extend T::Helpers
+
+  # This base class enforces no constraints on its own.
+  # Individual subclasses use the `satisfy` DSL to define those constraints.
+  abstract!
 
   attr_reader :name, :cask, :download
 
   def initialize(tags = [])
-    # Only allow instances of subclasses. This base class enforces no constraints on its own.
-    # Individual subclasses use the `satisfy` DSL to define those constraints.
-    raise "Do not call `Requirement.new' directly without a subclass." unless self.class < Requirement
-
     @cask = self.class.cask
     @download = self.class.download
     tags.each do |tag|
diff --git a/Library/Homebrew/standalone/sorbet.rb b/Library/Homebrew/standalone/sorbet.rb
index 9cd7fa24a8df6..406582618d2e1 100644
--- a/Library/Homebrew/standalone/sorbet.rb
+++ b/Library/Homebrew/standalone/sorbet.rb
@@ -8,7 +8,9 @@
 # In the future we should consider not doing this monkey patch,
 # if assured that there is no performance hit from removing this.
 # There are mechanisms to achieve a middle ground (`default_checked_level`).
-unless ENV["HOMEBREW_SORBET_RUNTIME"]
+if ENV["HOMEBREW_SORBET_RUNTIME"]
+  T::Configuration.enable_final_checks_on_hooks
+else
   # Redefine `T.let`, etc. to make the `checked` parameter default to `false` rather than `true`.
   # @private
   module TNoChecks
diff --git a/Library/Homebrew/test/formula_spec.rb b/Library/Homebrew/test/formula_spec.rb
index 7346b11226d40..f2f9a993fbae5 100644
--- a/Library/Homebrew/test/formula_spec.rb
+++ b/Library/Homebrew/test/formula_spec.rb
@@ -60,6 +60,11 @@
       expect { klass.new }.to raise_error(ArgumentError)
     end
 
+    specify "formula instantiation without a subclass" do
+      expect { described_class.new(name, path, spec) }
+        .to raise_error(RuntimeError, "Do not call `Formula.new' directly without a subclass.")
+    end
+
     context "when in a Tap" do
       let(:tap) { Tap.fetch("foo", "bar") }
       let(:path) { (tap.path/"Formula/#{name}.rb") }
diff --git a/Library/Homebrew/test/requirement_spec.rb b/Library/Homebrew/test/requirement_spec.rb
index 7789e2f5091f1..0024127c20bf2 100644
--- a/Library/Homebrew/test/requirement_spec.rb
+++ b/Library/Homebrew/test/requirement_spec.rb
@@ -10,6 +10,13 @@
 
   let(:klass) { Class.new(described_class) }
 
+  describe "base class" do
+    it "raises an error when instantiated" do
+      expect { described_class.new }
+        .to raise_error(RuntimeError, "Requirement is declared as abstract; it cannot be instantiated")
+    end
+  end
+
   describe "#tags" do
     subject(:req) { klass.new(tags) }
 
@@ -52,6 +59,17 @@
     describe "#fatal is omitted" do
       it { is_expected.not_to be_fatal }
     end
+
+    describe "in subclasses" do
+      it "raises an error when instantiated" do
+        expect do
+          Class.new(described_class) do
+            def fatal? = false
+          end
+        end
+        .to raise_error(RuntimeError, /The method `fatal\?` on #{described_class.name} was declared as final/)
+      end
+    end
   end
 
   describe "#satisfied?" do