diff --git a/girwriter.c b/girwriter.c
index 1b61de03e..bb82a46f6 100644
--- a/girwriter.c
+++ b/girwriter.c
@@ -61,6 +61,9 @@ xml_element_free (XmlElement *elem)
   g_slice_free (XmlElement, elem);
 }
 
+static void
+xml_printf (Xml *xml, const char *fmt, ...) G_GNUC_PRINTF (2, 3);
+
 static void
 xml_printf (Xml *xml, const char *fmt, ...)
 {