diff --git a/libratbox/src/crypt.c b/libratbox/src/crypt.c
index 86c3c3f29..b557cf5d3 100644
--- a/libratbox/src/crypt.c
+++ b/libratbox/src/crypt.c
@@ -1567,7 +1567,7 @@ static char *rb_sha256_crypt_r(const char *key, const char *salt, char *buffer,
 	rb_sha256_init_ctx(&alt_ctx);
 
 	/* For every character in the password add the entire password.  */
-	for (cnt = 0; cnt < (size_t)(16 + alt_result[0]); ++cnt)
+	for (cnt = 0; cnt < key_len; ++cnt)
 		rb_sha256_process_bytes(key, key_len, &alt_ctx);
 
 	/* Finish the digest.  */