diff --git a/ChangeLog b/ChangeLog
index 51f2478487..937cedfd57 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+Tue Oct  6 06:32:52 2015  Koichi Sasada  <ko1@atdot.net>
+
+	* proc.c: enable optimization of Proc#call.
+	  [Feature #11569]
+
+	* NEWS: write about this optimization and incompatibilities.
+
+	* test/ruby/test_backtrace.rb: catch up this fix.
+
 Tue Oct  6 04:41:03 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* vm_insnhelper.c: solve goto spaghetti.
diff --git a/NEWS b/NEWS
index 10e5e11d73..8a4141e198 100644
--- a/NEWS
+++ b/NEWS
@@ -65,6 +65,12 @@ with all sufficient information, see the ChangeLog file.
     true when the receiver is positive and negative respectively.
     [Feature #11151]
 
+* Proc
+
+  * Proc#call (and also #[], #===, #yield) are optimized.
+    Backtrace doesn't show each methods (show block lines directly).
+    TracePoint also ignore these calls. [Feature #11569]
+
 * Thread
   * Thread#name, Thread#name= are added to handle thread names [Feature #11251]
 
diff --git a/proc.c b/proc.c
index 6370904109..b84a4fc9d9 100644
--- a/proc.c
+++ b/proc.c
@@ -733,7 +733,7 @@ rb_block_clear_env_self(VALUE proc)
  *     	from prog.rb:5:in `<main>'
  *
  */
-
+#if 0
 static VALUE
 proc_call(int argc, VALUE *argv, VALUE procval)
 {
@@ -759,6 +759,7 @@ proc_call(int argc, VALUE *argv, VALUE procval)
     RB_GC_GUARD(passed_procval);
     return vret;
 }
+#endif
 
 #if SIZEOF_LONG > SIZEOF_INT
 static inline int
@@ -2803,7 +2804,6 @@ Init_Proc(void)
     rb_undef_alloc_func(rb_cProc);
     rb_define_singleton_method(rb_cProc, "new", rb_proc_s_new, -1);
 
-#if 0 /* incomplete. */
     rb_add_method(rb_cProc, rb_intern("call"), VM_METHOD_TYPE_OPTIMIZED,
 		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
     rb_add_method(rb_cProc, rb_intern("[]"), VM_METHOD_TYPE_OPTIMIZED,
@@ -2812,12 +2812,7 @@ Init_Proc(void)
 		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
     rb_add_method(rb_cProc, rb_intern("yield"), VM_METHOD_TYPE_OPTIMIZED,
 		  (void *)OPTIMIZED_METHOD_TYPE_CALL, 0);
-#else
-    rb_define_method(rb_cProc, "call", proc_call, -1);
-    rb_define_method(rb_cProc, "[]", proc_call, -1);
-    rb_define_method(rb_cProc, "===", proc_call, -1);
-    rb_define_method(rb_cProc, "yield", proc_call, -1);
-#endif
+
     rb_define_method(rb_cProc, "to_proc", proc_to_proc, 0);
     rb_define_method(rb_cProc, "arity", proc_arity, 0);
     rb_define_method(rb_cProc, "clone", proc_clone, 0);
diff --git a/test/ruby/test_backtrace.rb b/test/ruby/test_backtrace.rb
index 7fbfddf94c..3076f37017 100644
--- a/test/ruby/test_backtrace.rb
+++ b/test/ruby/test_backtrace.rb
@@ -79,10 +79,10 @@ class TestBacktrace < Test::Unit::TestCase
         cs << caller(5)
       }.call
     }.resume
-    assert_equal(3, cs[0].size)
-    assert_equal(2, cs[1].size)
-    assert_equal(1, cs[2].size)
-    assert_equal(0, cs[3].size)
+    assert_equal(2, cs[0].size)
+    assert_equal(1, cs[1].size)
+    assert_equal(0, cs[2].size)
+    assert_equal(nil, cs[3])
     assert_equal(nil, cs[4])
 
     #