diff --git a/error.c b/error.c
index 9f4b79b7bb..6a73d375ec 100644
--- a/error.c
+++ b/error.c
@@ -2329,6 +2329,7 @@ syserr_eqq(VALUE self, VALUE exc)
  *      * FloatDomainError
  *    * RegexpError
  *    * RuntimeError -- default for +raise+
+ *      * FrozenError
  *    * SystemCallError
  *      * Errno::*
  *    * ThreadError