diff --git a/sys/dev/isci/isci_io_request.c b/sys/dev/isci/isci_io_request.c
--- a/sys/dev/isci/isci_io_request.c
+++ b/sys/dev/isci/isci_io_request.c
@@ -186,6 +186,7 @@
 			    cam_sim_path(isci_controller->sim),
 			    isci_remote_device->index, 0);
 
+			memset(&ccb_relsim, 0, sizeof(ccb_relsim));
 			xpt_setup_ccb(&ccb_relsim.ccb_h, path, 5);
 			ccb_relsim.ccb_h.func_code = XPT_REL_SIMQ;
 			ccb_relsim.ccb_h.flags = CAM_DEV_QFREEZE;