diff --git a/ChangeLog b/ChangeLog
index 2e2202f6e6..b535efeb4f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Dec 30 11:18:42 2015  Elliot Winkler  <elliot.winkler@gmail.com>
+
+	* lib/forwardable.rb (def_instance_delegator) fix delegating to
+	  'args' and 'block', clashing with local variables in generated
+	  methods.  [ruby-core:72579] [Bug #11916]
+
+	* lib/forwardable.rb (def_single_delegator): ditto.
+
 Wed Dec 30 09:58:56 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* object.c (rb_class_inherited_p): search the corresponding
diff --git a/lib/forwardable.rb b/lib/forwardable.rb
index cd15eeab0c..f27437af82 100644
--- a/lib/forwardable.rb
+++ b/lib/forwardable.rb
@@ -178,6 +178,10 @@ module Forwardable
   #   q.push 23  #=> NoMethodError
   #
   def def_instance_delegator(accessor, method, ali = method)
+    if method_defined?(accessor) || private_method_defined?(accessor)
+      accessor = "#{accessor}()"
+    end
+
     line_no = __LINE__; str = %{
       def #{ali}(*args, &block)
         begin
@@ -270,7 +274,11 @@ module SingleForwardable
   # the method of the same name in _accessor_).  If _new_name_ is
   # provided, it is used as the name for the delegate method.
   def def_single_delegator(accessor, method, ali = method)
-    str = %{
+    if method_defined?(accessor) || private_method_defined?(accessor)
+      accessor = "#{accessor}()"
+    end
+
+    line_no = __LINE__; str = %{
       def #{ali}(*args, &block)
         begin
           #{accessor}.__send__(:#{method}, *args, &block)
@@ -281,7 +289,7 @@ module SingleForwardable
       end
     }
 
-    instance_eval(str, __FILE__, __LINE__)
+    instance_eval(str, __FILE__, line_no)
   end
 
   alias delegate single_delegate