diff --git a/Library/Homebrew/cask/dsl/conflicts_with.rb b/Library/Homebrew/cask/dsl/conflicts_with.rb
index 5c9d64bc83..fc38c89f6f 100644
--- a/Library/Homebrew/cask/dsl/conflicts_with.rb
+++ b/Library/Homebrew/cask/dsl/conflicts_with.rb
@@ -23,7 +23,7 @@ module Cask
         options.assert_valid_keys(*VALID_KEYS, *ODEPRECATED_KEYS)
 
         options.keys.intersection(ODEPRECATED_KEYS).each do |key|
-          odeprecated "conflicts_with #{key}:"
+          Kernel.odeprecated "conflicts_with #{key}:"
         end
 
         conflicts = options.transform_values { |v| Set.new(Kernel.Array(v)) }
diff --git a/Library/Homebrew/cask/dsl/conflicts_with.rbi b/Library/Homebrew/cask/dsl/conflicts_with.rbi
deleted file mode 100644
index dd70de133c..0000000000
--- a/Library/Homebrew/cask/dsl/conflicts_with.rbi
+++ /dev/null
@@ -1,10 +0,0 @@
-# typed: strict
-# frozen_string_literal: true
-
-module Cask
-  class DSL
-    class ConflictsWith < SimpleDelegator
-      include Kernel
-    end
-  end
-end
diff --git a/Library/Homebrew/test/cask/dsl_spec.rb b/Library/Homebrew/test/cask/dsl_spec.rb
index 9b1ef7102f..df761eefd0 100644
--- a/Library/Homebrew/test/cask/dsl_spec.rb
+++ b/Library/Homebrew/test/cask/dsl_spec.rb
@@ -501,6 +501,14 @@ RSpec.describe Cask::DSL, :cask, :no_api do
         expect { cask }.to raise_error(Cask::CaskInvalidError)
       end
     end
+
+    context "with deprecated conflicts_with key" do
+      let(:token) { "conflicts-with-deprecated-key" }
+
+      it "loads but shows deprecation warning for deprecated key" do
+        expect { cask.conflicts_with }.to raise_error(Cask::CaskInvalidError, /is deprecated/)
+      end
+    end
   end
 
   describe "installer stanza" do
diff --git a/Library/Homebrew/test/support/fixtures/cask/Casks/invalid/conflicts-with-deprecated-key.rb b/Library/Homebrew/test/support/fixtures/cask/Casks/invalid/conflicts-with-deprecated-key.rb
new file mode 100644
index 0000000000..a8c1474787
--- /dev/null
+++ b/Library/Homebrew/test/support/fixtures/cask/Casks/invalid/conflicts-with-deprecated-key.rb
@@ -0,0 +1,11 @@
+cask "conflicts-with-deprecated-key" do
+  version "1.2.3"
+  sha256 "67cdb8a02803ef37fdbf7e0be205863172e41a561ca446cd84f0d7ab35a99d94"
+
+  url "file://#{TEST_FIXTURE_DIR}/cask/caffeine.zip"
+  homepage "https://brew.sh/conflicts-with-deprecated-key"
+
+  conflicts_with formula: "some-formula"
+
+  app "Caffeine.app"
+end