diff --git a/src/crapto1.h b/src/crapto1.h
index 7547344..fd97b15 100644
--- a/src/crapto1.h
+++ b/src/crapto1.h
@@ -37,6 +37,7 @@ struct Crypto1State* lfsr_recovery32(uint32_t ks2, uint32_t in);
 struct Crypto1State* lfsr_recovery64(uint32_t ks2, uint32_t ks3);
 
 void lfsr_rollback(struct Crypto1State* s, uint32_t in, int fb);
+uint32_t lfsr_rollback_word(struct Crypto1State *s, uint32_t in, int fb);
 int nonce_distance(uint32_t from, uint32_t to);
 #define FOREACH_VALID_NONCE(N, FILTER, FSIZE)\
 	uint32_t __n = 0,__M = 0, N = 0;\