diff --git a/KNOWNBUGS.rb b/KNOWNBUGS.rb
index 35a8e75876..b9ffabf212 100644
--- a/KNOWNBUGS.rb
+++ b/KNOWNBUGS.rb
@@ -5,3 +5,12 @@
 # This test file includes tests which point out known bugs.
 # So all tests will cause failure.
 #
+
+assert_equal "ArgumentError", %{
+  def s(a) yield a; end
+  begin
+    s([1, 2], &lambda { |a,b| [a,b] })
+  rescue ArgumentError => e
+    e.class
+  end
+}