diff --git a/ChangeLog b/ChangeLog
index d19ef12ba2..d75980f4ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Feb 20 19:27:02 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* include/ruby/ruby.h (HAVE_RB_SCAN_ARGS_OPTIONAL_HASH): for
+	  rb_scan_args() optional hash feature.  [Bug #7861]
+
 Wed Feb 20 18:02:26 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (target_os): do not strip -gnu suffix on Linux if
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 6debe428af..70b6769ec0 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1347,6 +1347,9 @@ VALUE rb_funcall_passing_block(VALUE, ID, int, const VALUE*);
 int rb_scan_args(int, const VALUE*, const char*, ...);
 VALUE rb_call_super(int, const VALUE*);
 
+/* rb_scan_args() format allows ':' for optional hash */
+#define HAVE_RB_SCAN_ARGS_OPTIONAL_HASH 1
+
 VALUE rb_gv_set(const char*, VALUE);
 VALUE rb_gv_get(const char*);
 VALUE rb_iv_get(VALUE, const char*);