diff --git a/advent.h b/advent.h
index 2cc2daa..d3a62ca 100644
--- a/advent.h
+++ b/advent.h
@@ -10,6 +10,7 @@
 #define MINTRS		50
 #define MAXTRS		79
 #define MAXPARMS	25
+#define INVLIMIT	7
 
 typedef struct lcg_state
 {