--- a/src/rules/rules.h	Sat Mar 29 14:46:33 2014 +0100
+++ b/src/rules/rules.h	Sat Mar 29 16:53:58 2014 +0100
@@ -41,6 +41,7 @@
 #define INVALID_MOVE_SYNTAX 1
 #define INVALID_POSITION    2
 #define AMBIGUOUS_MOVE      3
+#define NEED_PROMOTION      4
 
 #endif	/* RULES_H */