diff --git a/core/proc/ruby2_keywords_spec.rb b/core/proc/ruby2_keywords_spec.rb
new file mode 100644
index 0000000000..db35ca08da
--- /dev/null
+++ b/core/proc/ruby2_keywords_spec.rb
@@ -0,0 +1,63 @@
+require_relative '../../spec_helper'
+
+ruby_version_is "2.7" do
+  # Note: these specs should be synched with Module#ruby2_keywords specs
+  describe "Proc#ruby2_keywords" do
+    it "marks the final hash argument as keyword hash" do
+      f = ->(*a) { a.last }
+      f.ruby2_keywords
+
+      last = f.call(1, 2, a: "a")
+      Hash.ruby2_keywords_hash?(last).should == true
+    end
+
+    it "suppresses deprecation warning when calls a method" do
+      obj = Object.new
+      def obj.foo(*a, **b) end
+
+      f = -> (*a) { obj.foo(*a) }
+
+      -> { f.call(1, 2, {a: "a"}) }.should complain /Using the last argument as keyword parameters is deprecated/
+      f.ruby2_keywords
+      -> { f.call(1, 2, {a: "a"}) }.should_not complain
+    end
+
+    it "suppresses deprecation warning when calls another proc" do
+      g = ->(*a, **b) { }
+      f = -> (*a) { g.call(*a) }
+
+      -> { f.call(1, 2, {a: "a"}) }.should complain /Using the last argument as keyword parameters is deprecated/
+      f.ruby2_keywords
+      -> { f.call(1, 2, {a: "a"}) }.should_not complain
+    end
+
+    it "returns self" do
+      f = ->(*a) { }
+      f.ruby2_keywords.should equal f
+    end
+
+    it "prints warning when a proc does not accept argument splat" do
+      f = ->(a, b, c) { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain /Skipping set of ruby2_keywords flag for/
+    end
+
+    it "prints warning when a proc accepts keywords" do
+      f = ->(a:, b:) { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain /Skipping set of ruby2_keywords flag for/
+    end
+
+    it "prints warning when a proc accepts keyword splat" do
+      f = ->(**a) { }
+
+      -> {
+        f.ruby2_keywords
+      }.should complain /Skipping set of ruby2_keywords flag for/
+    end
+  end
+end