diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 5954b905e3cab9723116646069356ad7928c31d8..326f4cc7f92c932578870443f1421488501c25c0 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -174,6 +174,7 @@ cio_start_key (struct subchannel *sch,	/* subchannel structure */
 	CIO_TRACE_EVENT(4, sch->dev.bus_id);
 
 	orb = &to_io_private(sch)->orb;
+	memset(orb, 0, sizeof(union orb));
 	/* sch is always under 2G. */
 	orb->cmd.intparm = (u32)(addr_t)sch;
 	orb->cmd.fmt = 1;