diff --git a/include/crypto.h b/include/crypto.h
index 2dee4dc..5141f94 100644
--- a/include/crypto.h
+++ b/include/crypto.h
@@ -25,6 +25,7 @@ extern "C" {
 
 //MACROS
 #define WHY2_CHECKSUM_SEGMENT_SIZE 4 //SEGMENT SIZE FOR CALCULATING CHECKSUM
+#define WHY2_CHECKSUM_PRIME 5 //PRIME NUMBER FOR ROTATION
 
 //FUNCTIONS
 unsigned long why2_checksum_segment(char *input); //TOO LONG TO EXPLAIN, DEAL WITH IT. TREAT IT LIKE A NORMAL CHECKSUM