diff --git a/ext/objspace/lib/objspace.rb b/ext/objspace/lib/objspace.rb
index 98cb07bacd..b57c24583c 100644
--- a/ext/objspace/lib/objspace.rb
+++ b/ext/objspace/lib/objspace.rb
@@ -114,7 +114,7 @@ module ObjectSpace
   #  Dump the contents of the ruby shape tree as JSON.
   #
   #  If _shapes_ is a positive integer, only shapes newer than the provided
-  #  shape id are dumped. The current shape_id can be accessed using +RubyVM.stat(:next_shape_id)+.
+  #  shape id are dumped. The current shape_id can be accessed using <tt>RubyVM.stat(:next_shape_id)</tt>.
   #
   #  This method is only expected to work with C Ruby.
   #  This is an experimental method and is subject to change.