diff --git a/iptables-xml.c b/iptables-xml.c
index 71d5288..1bb2e20 100644
--- a/iptables-xml.c
+++ b/iptables-xml.c
@@ -29,7 +29,7 @@
 
 #ifndef IPTABLES_MULTI
 int line = 0;
-void exit_error(enum exittype status, char *msg, ...)
+void exit_error(enum exittype status, const char *msg, ...)
 {
 	va_list args;