diff --git a/ChangeLog b/ChangeLog
index 262b21a068..b3fb855e1e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Aug 29 13:22:43 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm.c (rb_thread_method_id_and_class): curried proc has no
+	  method.  [ruby-core:31871]
+
 Sun Aug 29 12:51:33 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* load.c (rb_provide_feature): clarify error message for frozen
diff --git a/test/ruby/test_proc.rb b/test/ruby/test_proc.rb
index 5a108d3a0f..1a473ae43d 100644
--- a/test/ruby/test_proc.rb
+++ b/test/ruby/test_proc.rb
@@ -792,4 +792,12 @@ class TestProc < Test::Unit::TestCase
       assert_equal([obj, nil], [a, b], '[ruby-core:24139]')
     end
   end
+
+  def test_curry_with_trace
+    bug3751 = '[ruby-core:31871]'
+    set_trace_func(proc {})
+    test_curry
+  ensure
+    set_trace_func(nil)
+  end
 end
diff --git a/vm.c b/vm.c
index 558e9805f6..5d249e584e 100644
--- a/vm.c
+++ b/vm.c
@@ -1394,7 +1394,7 @@ rb_thread_method_id_and_class(rb_thread_t *th,
 {
     rb_control_frame_t *cfp = th->cfp;
     rb_iseq_t *iseq = cfp->iseq;
-    if (!iseq) {
+    if (!iseq && cfp->me) {
 	if (idp) *idp = cfp->me->def->original_id;
 	if (klassp) *klassp = cfp->me->klass;
 	return 1;