diff --git a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
index 5d0e46d..f203606 100644
--- a/drivers/block/cciss_scsi.c
+++ b/drivers/block/cciss_scsi.c
@@ -93,11 +93,15 @@
 };
 
 #pragma pack(1)
+
+#define SCSI_PAD_32 4
+#define SCSI_PAD_64 4
+
 struct cciss_scsi_cmd_stack_elem_t {
 	CommandList_struct cmd;
 	ErrorInfo_struct Err;
 	__u32 busaddr;
-	__u32 pad;
+	u8 pad[IS_32_BIT * SCSI_PAD_32 + IS_64_BIT * SCSI_PAD_64];
 };
 
 #pragma pack()
@@ -202,9 +206,9 @@
 	stk = &sa->cmd_stack; 
 	size = sizeof(struct cciss_scsi_cmd_stack_elem_t) * CMD_STACK_SIZE;
 
-	// pci_alloc_consistent guarantees 32-bit DMA address will
-	// be used
-
+	/* Check alignment, see cciss_cmd.h near CommandList_struct def. */
+	BUILD_BUG_ON((sizeof(*stk->pool) % COMMANDLIST_ALIGNMENT) != 0);
+	/* pci_alloc_consistent guarantees 32-bit DMA address will be used */
 	stk->pool = (struct cciss_scsi_cmd_stack_elem_t *)
 		pci_alloc_consistent(hba[ctlr]->pdev, size, &stk->cmd_pool_handle);