diff --git a/sys/cam/cam_xpt.h b/sys/cam/cam_xpt.h
--- a/sys/cam/cam_xpt.h
+++ b/sys/cam/cam_xpt.h
@@ -145,8 +145,8 @@
 void			xpt_sim_poll(struct cam_sim *sim);
 
 /*
- * Perform a path inquiry at the request priority. The bzero may be
- * unnecessary.
+ * Perform a path inquiry at the request priority. bzero may be redundant for
+ * allocated CCBs, but for the on-stack CCBs it's required.
  */
 static inline void
 xpt_path_inq(struct ccb_pathinq *cpi, struct cam_path *path)