diff --git a/ChangeLog b/ChangeLog
index 7c21bc9da4..ff45283778 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Sun Dec 20 11:14:11 2015  Koichi Sasada  <ko1@atdot.net>
+
+	* proc.c (rb_mod_define_method): should check Symbol or not.
+	  [Bug #11850]
+
+	* test/ruby/test_method.rb: add a test.
+
 Sun Dec 20 11:01:57 2015  Koichi Sasada  <ko1@atdot.net>
 
 	* proc.c (rb_mod_define_method): fix notation.
diff --git a/proc.c b/proc.c
index cd083ec2bf..6d153c1b3e 100644
--- a/proc.c
+++ b/proc.c
@@ -1774,8 +1774,13 @@ rb_mod_define_method(int argc, VALUE *argv, VALUE mod)
 	rb_thread_t *th = GET_THREAD();
 	rb_block_t *block = rb_vm_control_frame_block_ptr(th->cfp);
 	if (!block) rb_raise(rb_eArgError, proc_without_block);
+
 	body = block->proc;
-	if (!body) {
+
+	if (SYMBOL_P(body)) {
+	    body = rb_sym_to_proc(body);
+	}
+	else if (!body) {
 	    body = rb_vm_make_proc_lambda(th, block, rb_cProc, TRUE);
 	}
 #endif
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index cc2c9873c5..1e5f05473c 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -939,4 +939,18 @@ class TestMethod < Test::Unit::TestCase
     assert_equal([:m1, :m2, :m3].sort, MethodInMethodClass.public_instance_methods(false).sort)
     assert_equal([].sort, MethodInMethodClass.private_instance_methods(false).sort)
   end
+
+  def test_define_method_with_symbol
+    assert_normal_exit %q{
+      define_method(:foo, &:to_s)
+      define_method(:bar, :to_s.to_proc)
+    }, '[Bug #11850]'
+    c = Class.new{
+      define_method(:foo, &:to_s)
+      define_method(:bar, :to_s.to_proc)
+    }
+    obj = c.new
+    assert_equal('1', obj.foo(1))
+    assert_equal('1', obj.bar(1))
+  end
 end