--- a/tools/checkstyle.xml	Mon Jan 07 14:42:41 2013 +0100
+++ b/tools/checkstyle.xml	Mon Jan 07 21:09:26 2013 +0100
@@ -345,7 +345,9 @@
 	<module name="FinalParameters">
 	    <property name="tokens" value="CTOR_DEF"/>
 	</module>
-	<module name="Indentation"/>
+	<module name="Indentation">
+	    <property name="severity" value="error"/>
+	</module>
 
 	<module name="TodoComment"/>
 	<module name="UpperEll"/>