diff --git a/core/kernel.rbs b/core/kernel.rbs
index dd1f624fd..f97b66fd6 100644
--- a/core/kernel.rbs
+++ b/core/kernel.rbs
@@ -1209,7 +1209,7 @@ module Kernel : BasicObject
   # -->
   # Equivalent to Proc.new.
   #
-  def self?.proc: () { () -> untyped } -> Proc
+  def self?.proc: () { (?) -> untyped } -> Proc
 
   # <!--
   #   rdoc-file=proc.c
diff --git a/test/stdlib/Kernel_test.rb b/test/stdlib/Kernel_test.rb
index 137726110..bd8e40e08 100644
--- a/test/stdlib/Kernel_test.rb
+++ b/test/stdlib/Kernel_test.rb
@@ -95,6 +95,11 @@ def test_autoload?
     end
   end
 
+  def test_proc
+    assert_send_type "() { () -> untyped } -> Proc", Kernel, :proc do end
+    assert_send_type "() { () -> untyped } -> Proc", Kernel, :proc do |a, b| end
+  end
+
   def test_rand
     assert_send_type "() -> Float", Kernel, :rand
     assert_send_type "(0) -> Float", Kernel, :rand, 0