diff --git a/module/zfs/metaslab.c b/module/zfs/metaslab.c
index f01a8893e2..f49a8adc68 100644
--- a/module/zfs/metaslab.c
+++ b/module/zfs/metaslab.c
@@ -117,6 +117,11 @@ int metaslab_prefetch_limit = SPA_DVAS_PER_BP;
  */
 int metaslab_smo_bonus_pct = 150;
 
+/*
+ * Should we be willing to write data to degraded vdevs?
+ */
+boolean_t zfs_write_to_degraded = B_FALSE;
+
 /*
  * ==========================================================================
  * Metaslab classes
@@ -1725,10 +1730,13 @@ top:
 
 		/*
 		 * Avoid writing single-copy data to a failing vdev
+		 * unless the user instructs us that it is okay.
 		 */
 		if ((vd->vdev_stat.vs_write_errors > 0 ||
 		    vd->vdev_state < VDEV_STATE_HEALTHY) &&
-		    d == 0 && dshift == 3) {
+		    d == 0 && dshift == 3 &&
+		    !(zfs_write_to_degraded && vd->vdev_state ==
+		    VDEV_STATE_DEGRADED)) {
 			all_zero = B_FALSE;
 			goto next;
 		}