diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 39a96c768102..c4f2a0ef7489 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -164,7 +164,7 @@ static int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml,
 #define MLDV2_MASK(value, nb) ((nb)>=32 ? (value) : ((1<<(nb))-1) & (value))
 #define MLDV2_EXP(thresh, nbmant, nbexp, value) \
 	((value) < (thresh) ? (value) : \
-	((MLDV2_MASK(value, nbmant) | (1<<(nbmant+nbexp))) << \
+	((MLDV2_MASK(value, nbmant) | (1<<(nbmant))) << \
 	(MLDV2_MASK((value) >> (nbmant), nbexp) + (nbexp))))
 
 #define MLDV2_QQIC(value) MLDV2_EXP(0x80, 4, 3, value)