--- mpt_cam.c	(revision 277209)
+++ mpt_cam.c	(working copy)
@@ -272,6 +272,10 @@ 
 		return (0);
 	}
 
+	ccb = cam_getccb(dev);
+	if (ccb == NULL)
+		return (ENOMEM);
+
 	/* Zero the rest of the ccb. */
 	bzero(&(&ccb->ccb_h)[1], sizeof(struct ccb_scsiio) -
 	    sizeof(struct ccb_hdr));