diff --git a/runtime/indent/docbk.vim b/runtime/indent/docbk.vim
index 6b807bb..297ad04 100644
--- a/runtime/indent/docbk.vim
+++ b/runtime/indent/docbk.vim
@@ -5,9 +5,15 @@
 " Latest Revision:  2004-05-22
 " arch-tag:	    3d073af7-1d69-42a2-99ad-9a49a21eb28f
 
+if exists("b:did_indent")
+    finish
+endif
+
 " Same as XML indenting for now.
 runtime! indent/xml.vim
 
-setlocal indentexpr=XmlIndentGet(v:lnum,0)
+if exists('*XmlIndentGet')
+  setlocal indentexpr=XmlIndentGet(v:lnum,0)
+endif
 
 " vim: set sts=2 sw=2: