diff --git a/ChangeLog b/ChangeLog
index b2c764082f..6739c78123 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Nov 26 20:47:28 2014  Masaya Tarui  <tarui@ruby-lang.org>
+
+	* ext/continuation/continuation.c (Init_continuation): obsolete callcc.
+	  first step of [Feature #10548].
+
 Wed Nov 26 19:57:54 2014  Koichi Sasada  <ko1@atdot.net>
 
 	* test/ruby/test_gc.rb (test_latest_gc_info): do test separately
diff --git a/ext/continuation/continuation.c b/ext/continuation/continuation.c
index ae69b66cd8..71b52db539 100644
--- a/ext/continuation/continuation.c
+++ b/ext/continuation/continuation.c
@@ -1,8 +1,11 @@
 
+#include "ruby/ruby.h"
+
 void ruby_Init_Continuation_body(void);
 
 void
 Init_continuation(void)
 {
+    rb_warn("callcc is obsolete; use Fiber instead");
     ruby_Init_Continuation_body();
 }