diff --git a/src/libsm/sm-common.c b/src/libsm/sm-common.c
index 87d5907f..144fe86d 100644
--- a/src/libsm/sm-common.c
+++ b/src/libsm/sm-common.c
@@ -359,7 +359,7 @@ sm_incr_ssc(unsigned char *ssc, size_t ssc_len)
 	if (!ssc)
 		return;
 
-	for (ii = ssc_len - 1;ii >= 0; ii++)   {
+	for (ii = ssc_len - 1; ii >= 0; ii--)   {
 		*(ssc + ii) += 1;
 		if (*(ssc + ii) != 0)
 			break;