--- ./lightdm-1.8.5/src/logger.c	2013-10-09 16:16:00.000000000 +1300
+++ ./lightdm-1.11.9/src/logger.c	2014-05-29 17:27:49.000000000 +1200
@@ -3,7 +3,7 @@
 G_DEFINE_INTERFACE (Logger, logger, G_TYPE_INVALID);
 
 static void
-logger_logv_default (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap);
+logger_logv_default (Logger *self, GLogLevelFlags log_level, const gchar *format, va_list ap) __attribute__ ((format (printf, 3, 0)));
 
 static void
 logger_default_init (LoggerInterface *iface)