diff --git a/drivers/infiniband/hw/mlx4/mcg.c b/drivers/infiniband/hw/mlx4/mcg.c
index 3c3b54c..44ff480 100644
--- a/drivers/infiniband/hw/mlx4/mcg.c
+++ b/drivers/infiniband/hw/mlx4/mcg.c
@@ -233,7 +233,8 @@
 
 	ib_query_ah(dev->sm_ah[ctx->port - 1], &ah_attr);
 
-	wc.pkey_index = 0;
+	if (ib_find_cached_pkey(&dev->ib_dev, ctx->port, IB_DEFAULT_PKEY_FULL, &wc.pkey_index))
+		return -EINVAL;
 	wc.sl = 0;
 	wc.dlid_path_bits = 0;
 	wc.port_num = ctx->port;