diff --git a/runtime/ftplugin/dtd.vim b/runtime/ftplugin/dtd.vim
index eed5ca6..6c08f66 100644
--- a/runtime/ftplugin/dtd.vim
+++ b/runtime/ftplugin/dtd.vim
@@ -37,3 +37,4 @@
 
 " Restore the saved compatibility options.
 let &cpo = s:save_cpo
+unlet s:save_cpo