diff --git a/README.md b/README.md
index c774e4c6..e02d16fe 100644
--- a/README.md
+++ b/README.md
@@ -245,11 +245,11 @@ can pass additional arguments that control the code output:
 ### Keeping copyright notices or other comments
 
 You can pass `--comments` to retain certain comments in the output.  By
-default it will keep JSDoc-style comments that contain "@preserve" or
-"@license".  You can pass `--comments all` to keep all the comments, or a
-valid JavaScript regexp to keep only comments that match this regexp.  For
-example `--comments '/foo|bar/'` will keep only comments that contain "foo"
-or "bar".
+default it will keep JSDoc-style comments that contain "@preserve",
+"@license" or "@cc_on" (conditional compilation for IE).  You can pass
+`--comments all` to keep all the comments, or a valid JavaScript regexp to
+keep only comments that match this regexp.  For example `--comments
+'/foo|bar/'` will keep only comments that contain "foo" or "bar".
 
 Note, however, that there might be situations where comments are lost.  For
 example: