diff --git a/glib/gmarkup.c b/glib/gmarkup.c
index 43bb0c7f8..99cabed68 100644
--- a/glib/gmarkup.c
+++ b/glib/gmarkup.c
@@ -45,7 +45,8 @@
  * The "GMarkup" parser is intended to parse a simple markup format
  * that's a subset of XML. This is a small, efficient, easy-to-use
  * parser. It should not be used if you expect to interoperate with
- * other applications generating full-scale XML. However, it's very
+ * other applications generating full-scale XML, and must not be used if you
+ * expect to parse untrusted input. However, it's very
  * useful for application data files, config files, etc. where you
  * know your application will be the only one writing the file.
  * Full-scale XML parsers should be able to parse the subset used by