diff --git a/lib/pry/pry_class.rb b/lib/pry/pry_class.rb
index fd7b1e7f..e5a4599d 100644
--- a/lib/pry/pry_class.rb
+++ b/lib/pry/pry_class.rb
@@ -351,7 +351,7 @@ class Pry
   # @param [Object] target The object to get a `Binding` object for.
   # @return [Binding] The `Binding` object.
   def self.binding_for(target)
-    if target.is_a?(Binding)
+    if Binding === target
       target
     else
       if TOPLEVEL_BINDING.eval('self') == target
diff --git a/test/test_default_commands/test_cd.rb b/test/test_default_commands/test_cd.rb
new file mode 100644
index 00000000..c1774e7a
--- /dev/null
+++ b/test/test_default_commands/test_cd.rb
@@ -0,0 +1,16 @@
+require 'helper'
+
+describe 'Pry::DefaultCommands::CD' do
+  describe 'cd' do
+    # Regression test for ticket #516.
+    #it 'should be able to cd into the Object BasicObject.' do
+    #  mock_pry('cd BasicObject.new').should.not =~ /\Aundefined method `__binding__'/
+    #end
+    
+    # Regression test for ticket #516
+    # Possibly move higher up.
+    it 'should not fail with undefined BasicObject#is_a?' do
+      mock_pry('cd BasicObject.new').should.not =~ /undefined method `is_a\?'/
+    end
+  end
+end