diff --git a/mmss/config.l b/mmss/config.l
index 33d9631..10c1a9d 100644
--- a/mmss/config.l
+++ b/mmss/config.l
@@ -41,6 +41,11 @@
 	 #include <cstdio>
 }
 
+%{
+	/* register is deprecated in C++11 */
+	#define register
+%}
+
 %s NEEDSPACE
 %s STRING
 %s COMMENT