diff --git a/README.EXT b/README.EXT
index c8c9342e16..a5e48a2a9d 100644
--- a/README.EXT
+++ b/README.EXT
@@ -1262,6 +1262,8 @@ Calls the function func with arg as the argument.  If no exception
 occured during func, it returns the result of func and *state is zero.
 Otherwise, it returns Qnil and sets *state to nonzero.  If state is
 NULL, it is not set in both cases.
+You have to clear the error info with rb_set_errinfo(Qnil) when
+ignoring the caught exception.
 
  void rb_jump_tag(int state)
 
diff --git a/README.EXT.ja b/README.EXT.ja
index ce2b30484a..6278a53c4e 100644
--- a/README.EXT.ja
+++ b/README.EXT.ja
@@ -1336,6 +1336,8 @@ VALUE rb_protect(VALUE (*func) (VALUE), VALUE arg, int *state)
   関数funcをargを引数として実行し, 例外が発生しなければその戻
   り値を返す．例外が発生した場合は, *stateに非0をセットして
   Qnilを返す．
+  rb_jump_tag()を呼ばずに捕捉した例外を無視する場合には，
+  rb_set_errinfo(Qnil)でエラー情報をクリアしなければならない．
 
 void rb_jump_tag(int state)