diff --git a/drivers/infiniband/hw/mthca/mthca_cq.c b/drivers/infiniband/hw/mthca/mthca_cq.c
index 6bd9f1393349c1d8e92e1c23bda605e14fa46846..1e1e336d3ef9715897088322e3452d5dd366379f 100644
--- a/drivers/infiniband/hw/mthca/mthca_cq.c
+++ b/drivers/infiniband/hw/mthca/mthca_cq.c
@@ -473,7 +473,7 @@ static void handle_error_cqe(struct mthca_dev *dev, struct mthca_cq *cq,
 	if (!(new_wqe & cpu_to_be32(0x3f)) || (!cqe->db_cnt && dbd))
 		return;
 
-	cqe->db_cnt   = cpu_to_be16(be16_to_cpu(cqe->db_cnt) - dbd);
+	be16_add_cpu(&cqe->db_cnt, -dbd);
 	cqe->wqe      = new_wqe;
 	cqe->syndrome = SYNDROME_WR_FLUSH_ERR;