--- a/ConfigTreeNode.py	Sun Jul 30 13:54:51 2017 -0700
+++ b/ConfigTreeNode.py	Mon Aug 07 14:28:29 2017 +0300
@@ -53,7 +53,7 @@
         </xsd:schema>""")
 
 NameTypeSeparator = '@'
-XSDSchemaErrorMessage = _("{a1} XML file doesn't follow XSD schema at line %{a2}:\n{a3}")
+XSDSchemaErrorMessage = _("{a1} XML file doesn't follow XSD schema at line {a2}:\n{a3}")
 
 class ConfigTreeNode:
     """